I'm not sure which has the most collectors, but I'll throw in for the 75s as my favorite.
The set gives Hammerin' Hank is due bookending the set, there are several Ryan cards, the Brett rookie is just a gorgeous card, and Mike Schmidt looks like Dirty Harry.
The '71 set will also eat up too much money and the horrid Ernie Banks overshadows the iconic Ryan, Clemente and Munson.
+1 for the 75 set
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