Well, lets see.
Left field has Pujols, Bonds, Manny, Garrett, Carlos Lee, Chipper, Berkman and Giles heading up the field before a drop off...
Center has Beltran, Wells, Preston W, Pierre, Giles, Andruw, and Johnny Damon that are near the top
Right has too many to name.
So Center is the weakest imo. Though there are plenty of guys that can play at more than one OF position. Burnitz is eligible at all 3. Matsui at 2, etc. It may be a good idea to pick one of those type of guys up to cover.