I am a set collector. I always want the entire set and at a minimum all variations listed in SCD, Beckett and the Registry. I also, like Anthony, want an unopened pack. He also forced me against my will to do the Salesman samples, but I resisted the boxes.
For Bowman I have done all the regular sets and variations but settled for wrappers rather than packs.(I think Mark meant the 54 Williams) I did not undertake the 1949 PCL set or the 52 and 53 Proof sets, because I did not think I could finish them.
For Fleer I used SCD and the Fleer Sticker Blog as a checklist and except for a couple of very scarce Quiz cards and two of the 3 # 80 Martin backs from the 60 set think I am pretty complete. But, probably will never complete the 1923 set
For Topps I am done with the base sets. Still one short on the 67 Stand Ups and two on the 55 Hocus Focus. I have settled for types for the 55 Stamps, 61 Dice, 66 Punch Outs, 70 Cloth and 71 Rookie Artists proofs since completing those seems impossible for me. I have about half of the 68 Discs but will likely stop there since I do not think I can complete that one either. Otherwise think I have anything listed for Topps in SCD through 1994 ( Just base sets, updates and Heritage after that.
My need for variations ultimately required me to go for both Mantles, Thompsons and Robinsons in the 52 set since SCD now lists both.
I Have the 5 sets from 1951 but not the 3 unissued proofs from the Current All Star set. Have settled for reproductions of those as I think those 3 will cost about $ 100 K or so.
With the exception of the 1923 Fleer set I have not ventured into pre war