I feel like either method has its own strengths and weaknesses, so it's difficult to say which is preferred. These are my personal observatons from playing each game multiple times:
Dragon Age: Origins (the silent protagonist)
Pros:
- Ability to fully decide what the character sounds like
- more options in dialog
- more resources open to other NPC voice actors doing their thing (connected to the previous point, I believe, since nothing is being spent on a PC voice.)
Cons:
- Written text doesn't always indicate how the NPC will react (e.g. telling Alistair "Yes, we're in love" when he questions you about Zevran, and then realizing that that's not a joke (even with the cheesy line), and having to cringe as he sadly breaks it off with you and disapproves a ton). No matter how much you roleplay the way your Warden says something, it doesn't change the fact that the in game NPCs will interpret it a specific way, so that kind of takes away player agency, in that regard.
- Awkward conversation pacing. NPCs will repeat their 'base' question after answering whatever you picked. Can be repetitive.
Dragon Age II (the characterized speaker)
Pros:
- Generally cohesive conversations. Because Bioware can script things a certain way, it's possible to pick an option that best exemplifies the personality your Hawke would have, while still allowing the conversation to follow the plot appropriately (usually).
- Entertaining. I really, really enjoyed the insanity of witty Hawke. S/he just said the weirdest things, and it was great. Because of that, I find DAII to be one of the easiest games to replay, out of all of them. I don't necessarily have to puzzle out what character I want to play to be entertained and engaged the whole way through (a lot of wardens died in Ostagar for me...
)
- Easier to implement as a cameo (I'm not commenting on whether or not I liked seeing Hawke again, or how well it was or wasn't done, I'm just pointing out that the set personalities make it easier to bring back characters, than say someone like the Warden, who never had a given personality)
- More opportunities to see the PC's face. I really enjoy taking screenshots of my characters, and occasionally will use them for references when commissioning art. In Origins, there were certainly opportunities to see the Warden's face, but having the camera pan to your character because they're talking makes this much easier.
Cons:
- player agency removed. There is less room to nitpick over how a character would say something. That, or it requires a lot more effort to fit in the discrepancies in the script to one's vision of a character.
- Awkwardness. No, Hawke. It's not okay to tell the Viscount to look for a silver lining in his son's death. Or whatever the actual phrase was. Point is, the lines aren't always great indicators.
- Potentially bad voice actors. I haven't experienced this myself, but it's reasonable to assume that someone out there hated the voice actor for Hawke so much that it was too distracting to play the game. So having only one VA can be an issue, but I don't think it's one that affects the majority of players, since Bioware is fairly good at finding good VAs.
Dragon Age: Inquisition (a neutral speaker)
Pros:
- (Supposedly) less mishaps involving the Inquisitor saying something very wrong. Not always the case for some people (myself included), but I believe that was the intent with the neutrality.
- More face shots (probably only a pro for me really, but oh well XD)
- Multiple voices. This was very much appreciated since it made replaying the game a bit easier, since I didn't have to absently wonder why my elf and human sounded the same.
- Better icons (in fact I want more). I really appreciated having a slightly better idea about how the Inquisitor was going to say something. I'd even go so far as to say that we could've used them more. I think Bioware should really make use of them, more often in the general chatter.
Cons:
- Not enough diversity in the general chatter. I think the Inquisitor could really have benefited from a more paragon/renegade style of dialog. The reason I use that example is because in general, the ME series tends to be pretty linear, but the way you go about things is pretty varied. I believe that had the Inquisitor had the option to punch out everyone who dissented, or be a goody two shoes, all in the name of stopping Corypheus, that might've benefited the game a lot.
- Still issues with the tag line not matching what the Inquisitor says all the time. I think if this could be improved, or some system implemented to give players a better idea of what was going to be said, I think that would help.
- Sometimes not enough ways to say something. I know it sounds silly, but I really wish that for the romance conversation options, we had more than one heart more often. Like, okay yes, I want to hit on that character, but do I really have to resort to using that line? Fiiiine. And so forth. But that might just be my pie in the sky wishlist speaking, more than realistic expectations XD
I think, overall, given what Bioware has showed us, I'd say that DAII's Hawke and personalities was my favorite method, simply for being as entertaining as it was. I greatly enjoyed both Origins and Inquisitions' PC, but I felt like I had to do more to make them feel alive to me, which is sometimes nice, and sometimes not. I do think what they started with Inquisition has potential though, and just needs to be tweaked.
Sorry it's so long D: if TL;DR, I overall prefer voiced protagonists.