It's funny how so many of us listen to or even hear things "differently". I remember a mate of mine having a graphic equaliser and the fun we had messing about with the settings. He always thought I liked too much treble ("tinny" according to him "crisp and clear" according to me). On the other hand, I felt he was always too bass-heavy ("deep and rich" to his ears, "muffled" to mine).
I've been listening to The Beatles all my life and I still don't particularly "remember" which versions are mono and which are stereo...I can't recall the nuances/variations of the version I'm not listening to at any given moment and so am unable to mentally compare them in my mind's ear. I'm a bit the same with Blu Ray vs DVD or HD vs "normal" or whatever - I see the one I'm watching, the other formats are, literally "out of sight and out of mind".
So please help me out here. Can someone suggest, say, six or ten Beatles numbers where the difference between mono and stereo is very pronounced. I'll then play them back to back and try and decide which, if either, I tend to prefer. Suffering as I do from completistitis, all versions/box sets are readily to hand.