I use Liverpool Airport more than Manchester because its so much easier to transit through, I fly often ( pre covid ) so I really have given both airports a good try over the years, but that really has nothing to do with getting to Exeter . I have been travelling to Exeter for years now and used to always fly. I moved to rail because from a time point of view there was no advantage in flying and I found with split tickets I could save money. After I did the trip walking to my local station, it really worked out better