With the exception of a few scarce 1920's Cuban issues and a few other obscure issues, I'm not a set collector, so I only have that particular bug on a few occasions. Shameless plug for a decent Billiken Lloyd, which would complete my HOF run in that set. I stupidly sold mine years ago. An Eggleston card would be cool too.
Since I'm more of a HOF/star type collector, my basic definition of success is finding a card of that type of player that I have long desired and looked for. Unfortunately, I still have lots of room to be successful