If I could listen to just ONE of the guys work?
If you mean Beatles, this is hardly possible, since most Beatles songs are a collaboration to some degree. And according to themselves, regardless of who originated the song, or how extensive the collaboration was, whatever the "other" guy added or took away seemed to be the just the thing to push the song from good to great.
Do I like the songs that John originated more? Or, that Paul originated more? Again, hardly. I like "Penny Lane" much more than I like "Strawberry Fields", and I like "Come Together" much more than I like "Maxwell's Silver Hammer". I can do without both "Hello. Goodbye" and "Good Morning, Good Morning", although in fairness I don't skip over them when they're playing. Paul's seemingly small "aaaaaaaaaaah ahhh" contribution to "A Day In The Life" as well as the orchestra stuff makes the song for me, as does John's lyrical and vocal contribution to "She's Leaving Home". Why the hell would I want to choose?
As far as solo recordings go, IMO, without Paul, I find at least 2/3 of John's recorded output boring and mundane, and I have no use whatsoever for songs that he uses to state his political views (in fact I find them offensive). Some of his solo output like "Woman is the Niggger Of The World" and "Cold Turkey" I wish I'd never heard. Without John, I think Paul hasn't completed a lyric in 30+ years of recording, and his eclectic style is can be far too out of control, to the point of distraction. Even "Band On The Run" (which I think is a great album, and is my favorite 70's post Beatles album) sounds lyrically unfinished to me. IMO Paul sings ABOUT things without ever actually telling you what it IS that he's singing ABOUT. "Band on The Run, Band on The Run, Band on The Run, Band on The Run". OK... what about them? His songs seem have no (or a weak) point or plot (this tendency goes back to the Beatles).
Listening to solo Lennon or solo McCartney makes me think 'God, how much better would this song be if <Lennon or McCartney> was involved... So I couldn't choose there either.
I find John to be far more poetic and clever than Paul. He knows how to 'resolve' a song, both lyrically and musically. But I find Paul to be much more creative, diverse, and original than John.
It's amazing to me how perfectly their talents complimented each other.