There are many mature control link protocols from many well establishes manufacturers. Crossfire is among the better or best but it also costs more since you need an external TX for any radio except the Tango or Tango2 which has built in crossfire. Until recently, I would have said FrSky was an easy choice to look at with the multi-protocol modules, but they seem dead set on blocking out anyone from using their protocol on any radio other than their own. You can buy a receiver and flash the Accst firmware on it, but it's a lot of fiddling around and problematic for even experienced hobbyist. Flysky has very good firmware support and is a safe choice. Spectrum has a bunch of good receivers with many supported in the multi-protocol module.
Since it looks like this is your first drone, my advice would be to choose a safe option like Spectrum or Flysky for your short/med range receiver and avoid getting a bunch of different receivers from different manufacturers. Sticking with fewer will help you get familiar with the update and binding processes and the ecosystem from that manufacturer. If you plan on pushing the range of your video transmitter, chose a protocol that will have longer range than your video so you won't have to worry about failsafing. In this case you would probably be looking at TBS crossfire, Tracer, Immersion RC Ghost or FrSky R9 (or ExpressLRS if you want open source). Again, look at them and decide which one best aligns with your objectives and budget. Many people use crossfire because it just works and you never have to worry about a failsafe. It's expensive compared to "free" protocols supported by the multi-module, but for many people it's worth the price due to a great user experience and ease of use.
I personally run crossfire on most of my drones and FrSky Accst on the few where crossfire isn't practical or needed. It's just the path I chose, but many others have different directions but as you get more quads just avoid getting a bunch of different mfg. receivers to make your life easier when it comes to updates and support. Knowing 1-2 systems is way easier than keeping up with 4 or 5 or 6.
funny. Is there a "mature" option that the T18 does support or better yet... of the 5 (5in1) protocols, which is most stable and usable for a noob. Thanks again.
