Well, on the one hand, Vlad's stats are probably better. Despite the fact that Arod "wins" in 3 categories to Vlad's 2, Vlad absolutely killed Arod in SB's, whereas the other categories are all pretty close. Also, in a 4x4 league, Vlad wins by a little more, since each wins 2 categories, and again spanks Arod in SB's.
But on the other hand, Arlo and Grenade Teeth are absolutely right. A shortstop with that kind of offensive talent is a definite find, whereas you can find a good-hitting outfielder in any corner drugstore (next to the robitussin). Maybe not Vladimir Guerrero quality, but still good.
Really, I don't see any reason why the top 4 picks in any roto draft this year would not be Arod, Vlad, Soriano, and the Big Unit. And, really Arod should always be the top pick. The only wildcard at that point is whether you value consistency (Vlad), positional scarcity (Soriano), or pitching. It's actually possible that Soriano could slip some more with some players who are not sold on his consistency, but the other 3 are pretty much cemented in, and Arod pretty much holds the top of the pile right now.