Planescape Torment: Later combat sequences. Chock full of spam and stupidity. Baator, Carceri and the Fortress are fine because you can just run like a *****, but Curst Prison requires you to kill one of the many guards to find a key. It's easy if you're a high level mage, but if you're not, expect to make a lot of trips back to the hermit to rest.
KoTOR 2: Same reason as above. Also, the ending, and not just because it was unfinished. Hey, your ending choices are to follow Revan, "stay here" to provide "advice" or just continue as normal. But the ending cutscene is only affected by your alignment. Lolwut?.
Mass Effect, both of them: Inconsequential exploration sidequests.
KoTOR 2: Same reason as above. Also, the ending, and not just because it was unfinished. Hey, your ending choices are to follow Revan, "stay here" to provide "advice" or just continue as normal. But the ending cutscene is only affected by your alignment. Lolwut?.
Mass Effect, both of them: Inconsequential exploration sidequests.