Diablo III: Reaper of Souls

They should probably allow for mobs to spawn more randomly and not just a very small set of combos. The way it's set up now, there are a couple of good spawns (weak monsters, high density) and some very bad spawns (strong monsters, low density), increasing the randomness with which the mobs are put onto a rift would help average out things.
Maps should also not have such a great discrepancy in size, specially corridor-type maps which punish you too severely for deaths compared to other maps.
That and take out pylons, or at least conduit, from GRs.