Ideally I'd say Skryim's, but the lack of response options and the frequently awful selections you're given mean I can't support that style. As I've said a few times, for every NPC response there should be at least two player options - it'd be so easy to have a couple options that lead to the same resposne but come from a subtly different angle. It'd let us feel
far more in control than the current "Let's go hunt some vampires" or "Not right now", which almost never reflects the kind of speech anybody I play as would use. Knights of the Old Republic was great because, although there were many clichéd and cartoonishly 'evil' responses, there were many shades of grey so you didn't have to choose between happy hero and moody/uptight. A great example is when I was invited to join a certain secretive faction (not the most obvious one) and I had to choose between "I don't know what to say" (as in I'm speechless, it's such an honour) and "It's about time you asked me".
Player dialogue is the only area in which I will say that Bethesda are outright lousy. There's no excuse for it, half the people on this board can write better than that. In such situations we should at least be given the option of a generic -Yes- -No-, this is why I loved the 'stay silent' option when speaking to Dark Brotherhood members.
So basically I'd rather have the earlier style if they insist on not hiring better writers.
Please make the effort with dialogue, Bethesda, you're letting yourselves down.
I like both equally. I love how Skyrim has more choices in conversations but I also like Oblivion where you had Rumor topics. Morrowind is even more indepth due to a low amount of voicing acting.
While the characters in MW do tend to speak for longer, hardly any of them have anything new to say at all and are just carbon copies of all the other guys in that location. The ones with unique dialogue typically have around three topics which they'll speak on - they could easily voice act this amount of speech. As other people have mentioned in other threads, a hybrid of the two might be ideal wherein they speak at length on non quest related issues in text (so people who don't want to read backstory etc can ignore it) and voice act the main dialogue.