You will get a lot of advice based on what brand people use.
In the past I have used Futaba FF9, Sanwa, Futaba ZHP
and then went to Spektrum where I remain, having said that when my grandson decided that I was going to "help" him at RC banger Racing I bought two FrSky. Cheap as chips and brilliant. I would NOThowever buy Quanum, it was the biggest heap of Cr*p I ever tried to use.
Buy what you can afford and whatever you feel comfortable with. Get 2.4 though if you're going to buy new.
When I started in RC Helicopters I was advised to buy the best TX I could afford as you tend to stick with that.I have heard good reports about the Orange range, if you can live with the colour