Ugh... I much prefer in game drops, especially for a game like Warhammer Quest. Beat the big baddie, expect a good drop. Beat the random dungeon trash, expect something like gold or a common drop or once in a while a good weapon / shield / trinket thing. Plus a system like that increases replayability - something like WoW, where you knew the boss dropped the Greatsword of Multiple Monster Slayings, and if you ran the damn instance enough you'd get it or at least have a shot at rolling on it (looking at you, stupid DPS druid that rolled on my holy 1h clearly designed for a pally mace back in Cataclysm before I had kids and had time to play things other than mobile games).
I understand booster packs from the monetary standpoint, but it almost seems to cheapen the gameplay feel.