Customisation is great, but I think the best games have a balance between giving you choices and making the main character...an actual freaking character. This is just my personal opinion, of course, but I think the most apt comparison would be comparing Mass Effect to Dragon Age: Origins.
You can tweak Commander Shepard, choose skills, back story and gender, but Commander Shepard is always Commander Shepard. There's a distinct personality there, which, of course, gets refined through in-game choices. Being fully voiced is a part of that, but not essential; the dialogue choices are set up that way.
Compare that to DA:O, where I spent ages customising my character, and I didn't get attached at all. Outside of the origin stories, I had no sense of who The Warden was, and even those early character pieces just got completely overshadowed by everything and everyone else. It wasn't even the fact that they weren't voiced, because I was fine with that in Neverwinter Nights. Maybe that was because the alignment system gave the character a distinct outlook that you could roleplay.
So, yeah, I like character customisation, and I like being able to choose gender, race/species or ethnicity especially (hey, why should, every character be a grizzled white dude?) but I'm willing to sacrifice a few sliders for the sake of a better story.
You know which game did character customisation the best? Saints Row 2. You could make your character completely unique, but they would always be fully voiced, with different voice sets to better suit your race and appearance. Seriously, the degree of customisation in that game was frankly insane. I have never seen such variety. And yet you were always playing a distinct character. It was absolutely fantastic.
I have never seen any other game balance character creation so well. Admittedly, they didn't have to deal with classes or stats like RPGs do, but as far as physical appearance and personality? Unrivalled.
