Main characters could be voiced, like the top 20 important ones.
Then a few others could have intro-voices, so that their first dialogue line is voiced.
Other than that: Texted dialogue.
I don't mind reading the dialogue, it'd feel weird with how dialogue is done in this game, would work better for an isometric/3rdPP design.
But I could handle it if it meant that more dialogue could fit into the game.
Of course, with dialogue that actually "do" something there has to be coding and scripting involved.
Still.
Let me just write something up from scratch to show how easy it is, it's currently 03:56:
Ysolve/Ysolda (whatever her name is in Whiterun)
Spoiler Player - I'm looking for work, do you have any advice on where I can find any?
Ysolve - You could ask the Jarl or go to the inn, although, I have a task I need help with.
Player a1 - Sorry, but I can't help you. (Bleh...)
Player a2 - What's on your mind?
Ysolve a1 - Oh... Okay. /end
Ysolve a2 - I asked a mercenary to get me some (what the hell was it called? Sleeping Tree Sap? Let's go with Tree Sap) Tree Sap from a crater to the west of Whiterun but he never came back and it's been a couple of days now. Could you go see if you can find him or the Tree Sap?
Player b1 - Sure.
Player b2 - How much is it worth your trouble?
Player b3 - Sorry, I have other things to do.
Player b4 - He's probably dead if it's been that long.
Player b5 - How about you come with me and get it, that way you don't need a mercenary to get you Tree Sap and can collect your own from watching me collect it. [Persuade] (Speech 80 required)
Ysolve b1 - Thank you so much! It's to the west of Whiterun, it's suppose to be in a crater of some sort, a tree that stands out. /end
Ysolve b2 - Well, I payed the other mercenary 200 gold (I have no idea how much gold it is, too long since I played this quest thingie), same price goes for you, 50 extra if you find out what happened to the other mercenary.
Ysolve b3 - Then why did you even ask me. /end
Ysolve b4 - Don't say things like that! He might be seriously hurt. By Azura... What if I sent him to his death..
Ysolve b5 - That... Sounds like a good plan actually, could help me financially to be more self sufficient. Okay, let's do it! /end (This means she'll become a temporary companion, she isn't strong though, so if she dies then she dies and quest is failed.)
Player b2a - Okay, I'll do it.
Player b2b - Increase it to 300 and I'll do it. [Persuade] (Speech 65 required)
Player b4a - I'm sorry, I'm sure he's fine.
Player b4b - Well, that's how life is, some die, some live, guess he finished the race before me, think he got a prize for it?
Player b4c - Sounds like you're concerned, I'll go see if I can find him.
Ysolve b2a - Great! It's to the west of Whiterun, it's suppose to be in a crater of some sort, a tree that stands out. /end
Ysolve b2b1 (failed) - Tsst... You're joking right? I'm not paying you that much.
Ysolve b2b2 (Success) - *sighs* Fine, I suppose I'm not gonna find anyone else in a while, and I really need that Tree Sap. It's to the west of Whiterun, it's suppose to be in a crater of some sort, a tree that stands out. /end
Ysolve b4a - I hope so... /end (She stops being worried about the tree sap and starts feeling bad about what she's done, you can no longer ask her about the tree sap, she doesn't want to talk about it anymore, you can on the other hand ask her about the mercenary and tell her you'll go find out what is fate is)
Ysolve b4b - You're a horrible person! Get away from me! /end (She refuses to talk to you after this)
Ysolve b4c - Really? Thank you, I can't stand the thought that I might have sent someone to his death for a small errand.. I sent him to the west of Whiterun to a crater. /end
Player b2b1 (failed) - Fine, I'll do it for the original fee then.
Ysolve b2b1 (failed2) - Okay, It's to the west of Whiterun, it's suppose to be in a crater of some sort, a tree that stands out. /end
And now it's 04:18, it took me 22 minutes to write this and I'm a complete amateur, not to mention that Bethesda had YEARS to write Skyrim.
So yes, text is superior IMO to voice acting, cause voice acting will always limit the amount of dialogue they can fit into the game.