First thing that came to mind - high grade T3s. I don't think there's a set with better artwork.

If money were no object, I'd finish the set that I've been working on for a few years now: E135's.

I'm not sure I would build any complete set even if money were no object. I'd probably still collect the way I do now, buying cards I like. Only higher grade examples as well as cards currently out of my range.

I might try to get one of every Ruth card ever made if a player run counts.

Hof
 

If money were no object, I would collect every HOF card in every set.
From Old Judge to 1980 Topps and everything in between,

While I enjoy collecting sets, I have balked at even starting some since there are too many cost prohibitive big names in some of them and way too many commons... (I'm talking about you T206)

Andy's proposal takes care of that!
PS- Neither Don Money or Norm Cash made the HOF.
But this silly quest would take a lot of currency !!