I think I like the one that is generally regarded as the least interesting Ring opera the most - Das Rheingold. It's not as long winded and more action packed than the other three. I kinda enjoy Die Walkure also. I only listened to the other two once (I have the complete Solti cycle on cd). It's an awesome piece of work, I'm sure - but maybe it's all a bit over my head and I won't blame my own lack of patience or understanding on Wagner. I can manage to listen to the whole cycle when I limit myself to one act per day though - gotta try that again someday.
But Das Rheingold I really like. I even have it on DVD in a (thank God) traditional production friom Otto Schenk with James Levine conducting - very good. I said "thank God a traditional production" because otherwise I would probably have been done with The Ring for good. It's already a complicated/demanding work enough without some smart ass producer feeling the need to force his no doubt nonsensical interpretation of the thing down our throats.