The main reason I hate score match is because it has by far the biggest opportunity cost of playing the event match instead of normal songs. With token events you're playing normal songs all the time, so it counts towards song goals, and you can use random to get box points faster. Medley and challenge festivals have ways to boost your G/exp gain and rare reward drops, and medleys are actually more LP efficient than any other mode. Score matches? No friend supports or boost, no special rewards, no counting towards any goals. The only long-term thing it contributes towards is filling the points box, and before 4.0 it didn't even have that.
actually, after 4.0, SM is potentially the most EP/LP efficient
SM:
S/1 = 21.44 EP/LP
S/2.5 = 18.86 EP/LP
Medley:
3 EX S/S (assume +10% EP Option selected) = 18.45 (+ random supports)
3 EX S/B = 17.95
ChaFes:
5 EX S/S (same assumption as Medley) = 19.33 (+ random supports, potentially more then Medley)
5 EX S/B = 18.62
Token: (later on, huge bonus pts for taking muuuuch less time once we can mod LP/Tokens used)
25 EX + 9 Event EX S/S= 9.22 (S/B = 8.54)
scaled to 1 SR = 20.95 (19.4)
scaled to 2 SR = 22.13 (20.5)
scaled roughly to Tier 2 = ~18.5 (~17)
unless you're referring to exp/LP but that hardly matters at high Lvls and at low lvls, Medley isn't even maximally efficient below Lvl 70 (don't have 60 LP). it's also ironically arguably the least EP/LP efficient now
I do agree with SM having the largest cost opportunity and that's also why I dislike SM the most. it's simply the least newbie friendly, too (though a newbie can probably overreach in a Medley and fail)