Math (and spreadsheets) to the rescue! The following is a scoring I made based purely on the setlist. It factors in "how much of the set list do I like?" (as in percentage) and "how many songs are on here that I like?" (as in straight-up count), with a bias towards the latter, so that games with lots of songs that I like get some favor, even if I don't like the set list as a whole. (Examples include GH1 versus GH2, where GH1 had a higher percentage of songs I liked versus GH2, which had more songs I liked. GH2 won out.)
For those interested, the formula I used for what I call the "bias score" is (Percentage of setlist I like) + (Number of songs I like * 1.3), rounded.
GH1 (30/47) 63.83%, Bias score 103
GH2 (43/74) 58.11%, Bias score 114
GH80s (16/30) 53.33%, Bias score 74
GH3 (44/73) 60.27%, Bias score 117
GHA (13/42) 30.95%, Bias score 48
GHWT (36/86) 41.86%, Bias score 89
GHM (16/52) 30.77%, Bias score 52
GHSH (35/48) 72.92%, Bias score 118
GH5 (36/85) 42.35%, Bias score 89
BH (32/65) 49.23%, Bias score 91
GHVH (14/47) 29.79%, Bias score 48
GHWoR (38/93) 40.86%, Bias score 90
According to this, the only one I'm really missing out on is Smash Hits, but I don't care for the WT interface, so whatever.
EDIT: For reference's sake, the Rock Band on-disc setlist:
RB1 (35/58) 60.34%, Bias score 106
(RB1EU (41/67) 61.19%, Bias score 114)
RB2 (50/84) 59.52%, Bias score 125
LRB (30/45) 66.67%, Bias score 106
GDRB (18/44) 40.91%, Bias score 64
RB3 (54/83) 65.06%, Bias score 135
There's a natural bias towards Rock Band games anyway, since I've played all of these and found more songs I like on them than I have in the Guitar Hero series. To be fair, I tried to make sure that if I liked something in Rock Band I marked it down in the Guitar Hero lists, too. Still, the continued DLC support and the superior engine and interface always made Rock Band the winner in the battle for me.
I suppose further versions could better detail HOW much I liked a song (like how I prefer Ghostbusters over Song 2 over So What, even though I marked them all down as songs I liked), but this was enough work as is.