This is a really tough one. Both guys are good young hitters. Zimmerman is obviously more established and more experienced, but he followed up a very, very good rookie season with a rather lacklustre sophomore campaign. He frustrated a lot of people last year and seems to be doing the same again in 2008. Still, it's hard to pull the plug on a guy that is the heart and soul of his team's offense, put up 110 RBI as a rook, and is still just 24 (I believe).
Longoria is a guy that we have to be careful with. Ryan Braun's 2007 is fresh in our minds, so we're aware of what highly touted rookies are capable of doing. And Longoria has a lot of similarities to Braun: both third basemen, both sluggers immediately put in the middle of their team's lineups, both very polished for their ages...When it comes to Longoria, I think it's very easy to start dreaming of unrealistic possibilities (i.e. Braun V.2.0). He has no track record--and while we instinctively know that that's a knock against him, it's also irresistible to thrust all kinds of exciting fantasies as to what he's capable of doing (we don't do this with Zimmerman because we've seen the highs and we've seen the lows--and as one poster in this thread has even indicated, it's easy to believe that that means we've seen his best). But because we haven't seen Longoria's best (or his worst), we tend to imagine what it could be (and we usually tend to get a little carried away when we imagine--especially with Braun's atypical rookie season in our minds).
With all that said, I'm as much of a dreamer as the next guy. I know that for every Longoria, there are probably five Alex Gordons (guys with huge potential and expectations who don't deliver right away). Nevertheless, I can't help but wonder what Longoria could do this year and think that perhaps he could approach something akin to Braun's brilliance, even though I know how unlikely that is.
In short, I guess my gut says Longoria, my head says Zimmerman.viewtopic.php?f=26&t=342799