Bioshock, the MGS series, TF2, and the GTA series.
Bioshock was great. With all the great performances in that game, none of them shamed any of the others in contrast. Ryan was great."No it belongs to God." The disdain, the hatred! Great stuff.
About 100% of the MGS series is tied up in Codec and cutscenes, and if it weren't for the fact that I loved voice overs, there's no way I would have actually sit through almost everyone of them in all four games. On second playthroughs I still would listen to and watch a large number of them. Snake's voice was great, I honestly can't imagine any other voice in that role. I'm actually pissed that MGS4 is the last one he's in, because now I can't listen to him go on about whatever ridiculous dialogue was written.
"They are ninjas."
"NINJAS?"
"They have swords."
"SWORDS?"
Awesomeness.
As far as TF2, I've lost count of the amount of times I've quoted the announcer. That women's voice is great in Portal and TF2. But for all the time's I repeated a line trying to capture his disdain and harshness, I've never quoted GLADOS. Plus the voices of all the player classes put it over the top.
The GTA series speaks for itself.
Oblivion. It pains me to say it, but it wasn't good. It's not that any individual actor was a total idiot, it's just that you have maybe a dozen actors reciting the vast majority of lines, of which there are about a billion. They mail it in, misread scenes, and do the same fucking voice for a hundreds of characters. There's nothing wrong with any individual voice, but some of the gender/race combos just seemed to phone it in whole sale, with no passion of flair.
"I'm reading lines without stumbling, and speaking clearly. This is obviously all you need to do to collect a pay check."
If they did this in Fallout 3, and it likes they might have, I will be sorely disappointed.
TLDR
Good:
MGA
GTA
Bioshock
Team Fortress 2
Bad:
Oblivion
Fallout 3(?)