Acceptably buggy. Hmmm.
Morrowind, maybe Oblivion. By the time Fallout and Skyrim rolled around, I really got the not accepting the excuse anymore when they should've fixed their crap by then. (It took 3 tries to not have the main quest glitch, numerous sidequests derailed, and both DLCs glitched out their main quests for me, Skyrim-wise. To say nothing of Oblivion's "you are a vampire forever" bug that they never fixed on PS3)
There's the occasional funny glitch, but it tends to show that the developer didn't test properly, and theres probably detrimental glitches lying around somewhere.