I'm going to be the annoying guy who complains "You don't have an 'It Depends' option."
Honestly, I don't see how this question can be answered in a vacuum. It really depends on what sort of mood I'm in, what the needs of the campaign are, and so forth.
I've played dwarven fighters in the past. I've played a warforged barbarian in an Eberron game at Origins. If someone made me choose right now, I'd probably say warforged for the novelty, but that could easily change tomorrow. Neither has an overt mechanical advantage over the other. (Sure, it looks like the warforged does, but I find it's not the case when you really get down to the numbers. They're both good at different things.)
So I'm abstaining from the poll. My answer is officially "Depends on my mood."