My favorites have more to do with memories than value
The first old card I ever owned:
I must've been about 9 when I got it.
The first T206 I ever owned:
Bought it from Mike Berkus at one of his Anaheim shows in the late 1970s, for twelve bucks. I remember because that was a big piece of my card budget for the day but it was a card I'd wanted for a while.
I met Hank Aaron:
nuf ced.