Which is my main radio brand? I also found this difficult to answer.
I have a Spektrum transmitter for all my indoor models mainly because a lot of them come RTF with Spektrum compatible receivers not because I am a Spektrum advocate.
I have two Futaba FF9 transmitters. One has an Assan module for my EDFs because Assan was my first 2.4GHz gear and it has NEVER let me down so I continue using it in EDF models because of possible electrical noise problems with high rpm brushless ESC/motor combos. I also have a Spektrum module which has been used in the FF9 on the odd occasion.
My other FF9 has a Futaba 35MHx module in it which I use on my old models that were originally 35MHz - frequency clashes never happen any more so why bother to change out the 35MHz gear - it works fine for me.