I use the 8FG, but that is probably overkill. Just make sure the one you select has a compatible receiver, there are some threads on this site talking about the Futaba receivers that do and don't work. The standard receiver with the 8FG works with the M5 and M10
I haven't tested them all, and as you saw on the other thread not all of them will work, but as I said above I use the 8FG on the M5 and M10, and it works. There will be others that work but I haven't tried them, others may have.
Sebastian any Futaba radio that has the ability to use an sBus receiver (except the the new FASSTest Rx's) would work fine. You need two additional controls besides the sticks. One rotary and one 3 way switch on the transmitter.