4" Freestyle / 5" Long Range
Here you'll find links to the best performing products for 4" Freestyle and 5" Ultralight drones based on my testing over on AOS Labs and my own experience and research. Some of these links are affiliate links (affiliate policy).
Motors
EMAX ECO II 2004
The Emax ECO II is a solid mid range motor at an exceptionally low price point. These 2004 motors provide comparable power and efficiency to motors costing twice as much. They are well matched to a 5" biblade, a 4" triblade, or 3.5" bullnose prop.
RCinPower GTS V3 2104
A beautifully made and high performance 2104 motor from RCinPower. Whether you go for the M2 mouting system (you will need to drill out your props by hand) or the standard T-mount version this is a fantastic motor for 4" freestyle or 5" Ultralight builds.
T-Motor F2004 1700KV/3000KV Motor
It's hard not to recommend a T-motor product when one exists in the right size and KV for your application. The F2004 1700Kv is well matched to a 6S ultralight 5" setup. The 3000KV is better for 3.5 - 4" setups on 4S.
Electronics Stack
iFlight Borg 5S 60R Stack
An interesting FPV racing stack from iFlight. A combination of a chip style antenna and a U.FL connection for an external antenna provides the option to run without an external antenna for super clean builds or add one for better range/penetration. I would always add a small T-style U.FL even for close range use to give the best link stability at the highest ELRS packet rates. The flat flex cable between the ESC and FC is a strange choice when SH1.0 has been a common standard and aan FFC doesn't seem to be any better or worse than SH1.0. A modern gyro (ICM42688) and 16MB of flash storage set you up for success with tuning. A 12V BEC with a switch and built in Analog OSD is a nice feature for analog pilots using VTXs that don't support up to 8S voltage. An 8S ESC with a 65A burst current rating (which is believeable from my testing!) provide all the power you need for a 5" race build. For digital racing it's worth checking out HDZero's stack but for Analog this is hard to beat.
HDZero Halo Stack
HDZero made an FC+ESC stack! This has the most complete range of features for DIGITAL Racers and Freestyle pilots that I've seen (but NO ANALOG OSD). Integrated 2.4GHz diversity ELRS receiver with support for 2x Standard U.FL antennas. 16MB of Blackbox storage for tuning. 5V/4A and 9V/3A BECs to power all your peripherals (especially if they don't natively support 8S voltage) as well as 4x free UARTs and an I2C Bus. An 8S capable ESC with full size FETs and a 100A burst rating. There are different versions, I would choose the ICM 42688 Gyro (modern and more reliable than current MPU6000s) and either the BLHeli32 or AM32 ESC (they both perform well in my testing).
GEPRC F722 AIO - F722 FC+ 35A 2S-6S BLS ESC
For up to 4" Props a 25mm AIO is where it's at. This AIO has everything: 6S 35A rating, F7 processor, DJI Plug and 16MB of Blackbox storage. Yes please!
A great 20 x 20 mm budget electronics stack. The 35A rating will be suitable for most 5" builds UNLESS you are using the most powerful 2207 motors available (e.g. AOS Supernova). Don't let anyone tell you an F4 + 35A BLHeli_S is not enough to have an amazing FPV experience!
SpeedyBee F405 Mini Stack - F405 V3 FC + 35A 3-6S BLHeli_S 4-in-1 ESC - 20x20
A great 20 x 20 mm budget electronics stack. The 35A rating will be suitable for most 5" builds UNLESS you are using the most powerful 2207 motors available (e.g. AOS Supernova). Don't let anyone tell you an F4 + 35A BLHeli_S is not enough to have an amazing FPV experience!
Skystars Fly Stack - F722 Mini HD Pro FC + KM55 55A AM_32 3-6S 4-in-1 ESC - 20x20
This is the dark horse of 20 x 20 mini stacks with a very special secret. F7 processor and 55A AM_32 ESC. AM_32 outperforms BLHeli_32 on my test stand and depite my best efforts torture testing motors I have been unable to kill this thing. For a high power 5" quad I wouldn't buy anything else today.
Holybro Kakute G4 AIO - G4 FC + 35A AM_32 ESC
A 25mm AIO with 16MB of Blackbox and DJI plug paired with a 35A AM_32 ESC. Sign me up.
VTX
DJI O4 Air Unit
This lightweight air unit supports up to 4K/60FPS onboard recording in a lightweight form factor. The recording quality is a huge step forward for micro quads which cannot carry a Naked GoPro. The voltage range (2-3S) is quite limiting if you don't use a flight controller with an onboard BEC to provide power although there are even some 1S FCs now that include a step up voltage regulator for O4! This is the first time a DJI has released a compelling VTX for toothpick and micro drones and in many ways that makes this more important than the O4 Pro for sub250g pilots.
DJI O4 Pro Air Unit Pro
DJI latest Air unit supports onboard recording up to 4K/120fps at 100 MBps a 155 degree FOV and a large 1/1.3" sensor for even better fidelity and visual quality. As with all DJI Air units the price point is quite high but the overall user experience is very good. The camera has a strange mounting pattern which does not fit all FPV frames, make sure you check out the V5 versions of AOS frames which support DJI O4 Pro. If the quality of the onboard recording is critical for you this will be a worthwhile upgrade over O3. If not then you may want to stick with the O3 system for now.
Walksnail Moonlight Kit 4K Avatar VTX Kit
The top of the line Walksnail Avatar VTX. Onboard 4k60 recording and 1080p60 or 720p100 video in the goggles. The image quality is not as good as DJI O3 but the price is much more reasonable and this camera does better in low light.
Foxeer HDZero Race VTX
Foxeer made a HDZero Race VTX! I actually prefer the specs of this VTX to the HDZero one because it can be powered from up to 6S LiPo voltage! Everything else is the same as the HDZero Race V3.
HDZero Freestyle V2 VTX
True 1W output power for the HDZero system just got better. The smaller 30x30x14 mm form factor and 20mm M2 mounting pattern make this VTX perfect for 3" - 5" Freestyle drones and pilots who want the lowest possible latency of any FPV system available today. De-cased the VTX can be used on Lightweight 3" builds.
Rush Tank Ultimate Plus 5.8GHz VTX
A solid choice for Analog with a high transmit power and good reputation for reliability.
DJI O3
The DJI O3 system pushes digital FPV in a new direction. Here the focus is onboard recording and image quality at the expense of latency. It is a great looking system, some pilots are reporting issues with vibration sensitivity of the IMU used for electronic image stabilisation, hopefully this will be resolved in a future firmware update.
Receiver
RadioMaster XR3 Nano Multi-Frequency ELRS
This is a quality ELRS receiver from Radiomaster that supports full Diversity across 2x Antennas. There are versions with 900MHz, 2.4GHz or Dual-band (2.4Ghz + 900MHz) antennas. 2.4GHz is ideal for smaller builds and racing. 900MHz is perfect for larger long range builds. 2.4GHz + 900Mhz gives the option to use either band but be aware this receiver doesn't support Gemini Xband for concurrent dual band use.
RadioMaster XR4 Gemini Xrossband ELRS
This is a quality ELRS receiver from Radiomaster that supports Gemini for two concurrent radio links 2.4GHz and 900MHz. This gives the most secure link whether you're racing close range or flying long range. You can choose between 2.4GHz + 2.4GHz (ideal for racing) / 900MHz + 900Mhz (ideal for long range) / 2.4GHz + 900Mhz (maximum reliability if there is a risk of interference). Make sure you have a TX module that supports Gemini to get the full benefit.
BetaFPV SuperX Gemini Xross Receiver
This is a low cost ELRS receiver that supports Gemini for two concurrent radio links 2.4GHz and 900MHz. This gives the most secure link whether you're racing close range or flying long range. You can choose between 2.4GHz + 2.4GHz (ideal for racing) / 900MHz + 900Mhz (ideal for long range) / 2.4GHz + 900Mhz (maximum reliability if there is a risk of interference). Make sure you have a TX module that supports Gemini to get the full benefit.
MATEKSYS ExpressLRS 2.4GHz Receiver - ELRS R24 TD
I've made my mind up. I'm only recommending ELRS moving forward. At this point it does everything better than any other radio link. LoRa for range and penetration, yes. 1000Hz update rate for crazy low latency, yes. Loads of manufacturers are making receivers for ELRS and I think this diversity offering from Matek (antenna diversity only) is certainly among the best performing and most reliable.
Happymodel ExpressLRS Nano 2.4GHz EP1 RX
Happymodel were the first to bring out ELRS hardware and their EP1 and EP2 receivers closely follow the developers reference design and are incredibly tiny. I lean towards the EP1 as the UFL antenna is much higher performing than the ceramic antenna on the EP2.
Props
Gemfan Hurricane 4023
Gemfan manufacture durable and high performing props. Their Hurricane blade profile is more agressively tapered which improves efficiency while still providing good top end power. The main benefit of these props is that they support both T-mount and 5mm mounting!
HQProp 4x4.3x3 V1S
HQ make durable high performing props and their V1S blade profile combines efficiency with great top end thrust and power. The limitation with this prop is that it is only compatible with 5mm prop shafts.
HQProp Durable T5x3
This is an exceptionally efficient T-mount 5" prop, it's well matched to 2004/2104 size motors and perfect for 5" long range or 5" toothpick quads.
Batteries
GNB 850mAh 120C LiHv
A great performing pack for 4S 3" or 3.5" drones. Energy density, power density and voltage sag are all excellent. The larger 850mAh capacity will extend flight times compared to a typical 650mAh pack but is a little heavier, of course.
TATTU R-Line 750mAh
Tattu packs are expensive but you can't fault the performance. Strong burst performance and good energy density with minimal voltage sag. Similar performance to the 550mAh but scaled up!
XILO 850mAh 6s 100c Lipo Battery
850mAh on 6S is a good size for 5" Ultralights. A 100C rating is typically designed for flight applications. Anything less than 50C is for ground vehicles. Battery availability depends on where you live and who will ship LiPos to you. This is a good value option from XILO.