Vlad - He could hit .325 w/ 40 HR's and 120 RBI, along with 15-20 SB, if those numbers aren't even a little better by year's end. He is an injury risk, but he plays in a strong lineup. (look for .327-41-124-17)
Beltran - He is a second half player. He should hit just over .300 with 25-30 HR's,over 100 RBI and sround or over 30 bases. He is in a weaker lineup, but as long as he's 100%, he is less of an injury risk. (look for .303-31-107-34)
I like Vlad a little more, but you can't go wrong with either.