I know exactly where you're coming from mate! I wouldn't say I was a lover of the genre completely. A lot of it leaves me cold. - I'm all for complex music, providing it's full of hooks and melody I can get into, and I love concept pieces that I can get into the atmosphere of, but I find a lot of Prog too convoluted and pretentious. Intelligent for the sake of it.
I would never in a million years put either Marillion or Fish into that category. They cross boundaries as far as I'm concerned. - I do have a lot of what would be termed 'Prog' in my music collection, such as Pink Floyd, Genesis, Anathema, Porcupine Tree, Pendragon, and a few others, but again, this is just what I would term 'great music', regardless of genre.