The video link is the part of an FPV build people agonise over most, and reasonably so it is what you actually experience while flying, and it is usually the most expensive decision. There are four realistic options. None of them is best at everything.
Analog
The original system, and still in wide use. A 5.8GHz analog transmitter sends a standard-definition composite signal to your goggles. The picture is soft, noisy, and degrades into static as you fly further out.
Strengths: cheapest by a wide margin. Extremely low latency. Degrades gracefully the image gets noisier and noisier but you keep flying, and you can usually get home on a picture that is mostly static. Enormous ecosystem of cheap parts. Everything is interoperable: any analog VTX works with any analog goggle.
Weaknesses: the picture quality is genuinely poor by modern standards, and after using a digital system it is hard to go back.
Choose it if: you are on a budget, you are racing, you fly cheap builds you expect to crash, or you want spares that cost very little to replace. Analog is not obsolete and pretending otherwise does new pilots a disservice.
DJI
The most polished digital system, currently built around the O4 air unit line. Excellent image quality, strong range, and it simply works out of the box.
Strengths: best-in-class picture. Very good penetration and range. Onboard recording at high quality. Setup is straightforward.
Weaknesses: highest cost, and a closed ecosystem DJI air units talk to DJI goggles and nothing else. Higher latency than analog, though acceptable for most pilots. When the link fails it tends to fail more abruptly than analog does, freezing rather than fading.
Choose it if: image quality is your priority, you are shooting cinematic footage, or you want the system that demands the least fiddling.
Walksnail (Avatar)
The main digital alternative to DJI, with the Avatar and Ascent lines. Very good picture, generally lighter air units, and more competitive pricing.
Strengths: excellent quality-per-rupee. Small, light air units suit micro and sub-250g builds well. Broad range of hardware options.
Weaknesses: also a closed ecosystem. Firmware has historically moved fast, which is good for features and occasionally inconvenient for stability.
Choose it if: you want digital quality without DJI pricing, or you are building light and need a small air unit.
HDZero
The system built specifically around low latency. HDZero uses a digital link designed to behave more like analog when conditions get difficult.
Strengths: the lowest latency of the digital systems, which matters enormously for racing. Degrades progressively rather than freezing. More open than DJI or Walksnail.
Weaknesses: picture quality sits below DJI and Walksnail. Smaller ecosystem.
Choose it if: you race, or you want digital clarity without giving up analog-like failure behaviour.
All three of the above sit in our digital VTX and air unit range.
How to actually decide
Ignore the specification sheets for a moment and answer three questions.
What are you flying for? Racing rewards latency and predictable degradation analog or HDZero. Cinematic flying rewards image quality DJI or Walksnail. General freestyle works well on any of them.
What is your crash budget? A digital air unit is an expensive component to destroy. If you are still learning and crashing regularly, analog is a far less painful place to make mistakes.
What weight can you carry? On a sub-250g build every gram counts, and the air unit is a meaningful fraction of the budget. Check the weight before you commit.
The thing most people get wrong
Goggles and air units are bought together and lock you into a path. Once you own DJI goggles, every quad you build tends to get a DJI air unit. So decide this one carefully more carefully than you decide on a frame or motors, which you can change freely later.
A reasonable approach: learn on analog, on a cheap build you do not mind breaking. Move to digital once your crashes have become rare enough that an expensive air unit is not a liability. Plenty of experienced pilots keep an analog quad in the bag regardless.
We stock analog, DJI, Walksnail and HDZero hardware. If you are weighing up two systems for a specific build, email info@aeroflow.in and we will talk it through with you.