Welcome avoard, Tim. Tough question, especially if you're looking at just this year. I actually do think highly of Blalock; hopefully, Texas will be patient with him if he struggles early on. It's certainly an amazing 3b class. Don't forget Hinske, either. He may not get as much press as the others, but he looks like the real deal.
Anyway, I think the question of who will have the best year depends on your needs (stop evading the question, Arlo
). If you're looking for the lowest risk, go with Burroughs. He's the safest bet to get playing time all year. If you need one of these guys as your everyday starter, go with him. Don't expect too much power, though.
In terms of potential, I like Blalock. If you have room on the bench and can afford to take a risk, I think he has the highest upside.
Ensberg lies somewhere in between those two, in terms of both risk and reward.
Hinske is the biggest sleeper. If he's still available in your league, trading Ensberg and picking up Hinske is an option worth considering.
If I had to choose just one, I'd probably go with Blalock, but that's more a matter of personal taste than anything else. Opinion on this question is all over the map at this point; I assume guys like cwebb or Dan, who both aren't as eager to take risks as I am, will think differently.
At any rate, no matter which of these guys you have, be patient. Their "objective" values, if such a thing exists, are roughly equal now (possibly with a slight edge to Burroughs), and you presumably picked up who you have for a reason. If Ensberg fits your style of play, hang on to him - he certainly has the talent to turn in some very solid numbers.
Not sure if this helps; hope some more folks chime in on this.