J-RPGs and I suppose most RPGs
I'd rather have 8-12 hours of genuine excitement, fun and engaging gameplay with a neat and compact story than 80-120 hours of meh, grinding and overly drawn out story. 10 times as long and per minute it is about a tenth as enjoyable may add up to just as good for many people but I just doesn't work that way for me.
But equally I dislike games where the single player is under 6 hours long... that is just taking the piss and extra modes like co-op and multiplayer should be mainly a supplement to, not a substitute of the single player. Though IW have always struggled to give the quantity to go with their quality, I remember COD2 and COD4 also ending fairly abruptly too.
I wish there were more games like Zelda: Ocarina of Time or Twilight Princess that take about 20 hours for the main quest and another 20 hours to max out to 100%. But that is more of an Action-RPG and I suppose you see a similar setup thing (yet still very distinct style) with Mass Effect or even Bioshock.