The Garmin stuff is WAY more intuitive than the Proline 21
I'd err on the other side of the fence. Completely agree that for VFR flying, Garmin is great. But for hard IFR all the time personally I find PL21 a lot more intuitive and simple to operate. It feels as though it was designed with skilled operators in mind, whilst I always feel Garmin think we're all a bit slow so triple check every command before it actually executes it.