I use a Spektrum AR610 which works fine but as a newcomer myself I don't have much to go on. The consensus I got at the event is that Spektrum transmitters/receivers are ones to get if you don't mind splashing out a little extra. There are a bunch of threads on here that could give you more info.

Here's the avatar pic, can't take any new ones because I'm not with the bot atm. If you're interested there's footage of it in battle floating about online. Just search for Extreme Robots Manchester 2018 Featherweight battle 1 on Youtube