This happens to be a fairly close position and everyone is strong here so its a good place to start.
Yankees- Mark Teixeira- The Yankees stole him right from under Boston's nose and it probably puts them at the top here. Clearly, he was the best free agent available this year. Teixeira consistently puts up EQA's over .300 ad theirs no reason to think he`ll fall of a cliff at 29. His glove is a big upgrade over Giambi as well. He`s a little overrated in the field but he`s generally solidly above average and good swing a few games that Giambi may have lost. All in all, this position was perenially a concern for a Yankees fans but we shouldn't have to worry about guys like Josh Phelps or Andy Phillips for a long time.
Rays- Carlos Pena- Once upon a time, the Yankees picked this guy up after he was released by the Tigers. While the likes of Andy Phillips and Miguel Cairo took turns being automatic outs Pena mashed away at AAA. Finally, he opted out of his contract and signed on with Boston. For some reason, I remember him hitting a walk-off home run for them but I`m a little fuzzy on that. Anyway, after the year he left as a free agent and signed on with the hapless Devil Rays. The past two years he`s been with them and Pena has quietly emerged as one of the better first baseman in baseball. Funny how things work out isn't it? Anyway, Pena has a glove and a bat that is comparable to Teixeira's and can crush the ball. He`s an underrated piece of the Rays.
Red Sox- Kevin Youkilis- At some point, somebody (Peter Gammons I`m looking at you) annointed this guy the heir to David Eckstein's throne as the grittiest man alive. As a result of this he went from being one of the most underrated players in baseball to being one of the most overrated. He`s clearly a very good player but not on the same level as Pena or Teixeira. This isn't just my Yankee bias either. In a career year he psoted an EQA of .321 which is great. However, Teixeira has beaten that three of the past four years. Pena crushed that in 2007 (his breakout year) and came close last year. All three of the projection systems available at fangraphs.com have Youkilis coming crashing down to earth next year as well. His glove is probably the best of the three but not significantly so. Its certainly not a weakness for Boston but he`s becoming very overrated.
Conclusion- Yankes- Rays- Boston- The Yanks are in the best situation here and Teixeira has a solid edge over Pena but both Tampa and Boston are getting more bang for their buck. As I said before, Youkilis is the worst of this very good group of players. However, its close enough that any of the three could emerge. If Youkilis' 2008 was more than just a career year then he could easily end up better than Pena and could beat out Teixeira for the All Star Game's starting spot as well.