Well, as one that started on Spektrum (had 3), then went to FrSky, but never had FlySky, and am now on Radiomaster, I will NEVER go back to Spektrum. OpenTX and multiprotocol are your friend, and proprietary radios are not. Cheap used stuff excluded.
In the end, it will really come down to what you want to fly or do RC.
RadioMaster running OpenTX has capabilities and flexibility that make it compatible with just about anything RC, whereas, some companies try to lock you in to their market and don't really care about progress and innovation unless it lines their pockets. I don't know enough about FlySky to know much other than the do run Open Firmware.