I definitely prefer voiced dialogue - though I don't particularly care if my own character is voiced or not.
Subtitles/text is a must, though.
I find "real voices" much more immersive than reading when it comes to dialogue - especially if the game is otherwise going for immersion and world simulation.
If it's a more tactical "bird's eye view" type of game, the voice acting becomes less important to me, because I'm not really playing for total immersion in that case.
On a more general note, I tend to find pure text-driven games overly verbose and often see writers losing their way trying to make an impression. I find that writers who understand the value of focusing on realism and plausible exchanges are rare, and most of them want to demonstrate their ability to use a lot of words in a sentence. Which is fine, I guess, if you're playing to experience the prose itself and not simply a story with interesting characters.
This is probably also why I can have a hard time getting into books - more so than I had in the past. It seems to me that the story often gets kind of lost in the battle of words.