what i'm playing right now is Arcanum. i'd dare say it's right up there with Morrowind in terms of variety and quests. just as an example, an NPC's reaction towards you can be judged by your race, good/evil alignment, magic/technology aptitude, gender, intelligence, strength, your companions and skill in haggle, persuasion, prowling, thievery, and of course your actions earlier on in the game. starting the game with a totally different character the second time literally changes the entire game. it's amazing.
i seriously wouldn't recommend playing the game without the patches though. Gamebanshee has them. the game's infamous for the bugs it used to have.
it's a shame the voice acting was only sparsely done. only the really important characters have them, such as people who could join you and a few major NPC's, but if it's used, it's very good apart from one or two characters. they really manage to pull off an entertaining british snobby accent sometimes. <img src="style_emoticons/<#EMO_DIR#>/laugh.gif" style="vertical-align:middle" emoid="

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i could go on for ages about the other cool stuff arcanum has, but as a summary, there's a very neat crafting system for technologists where they can use random junk to make something entirely new, the choice between realtime or turn-based combat (although the game never really was designed for realtime, so i wouldn't recommend it), your tech/magic aptitude determining combat advantage and the items you can use, at least 4 different endings, more quests in the capital city alone than PotC build 13 had in total, and a very realistic atmosphere if you know where to look (for that, i'd recommend the Tarantian library).