I play my "best" player wherever she is best-suited to play. That is, unless she is also my best pitcher or best catcher, in which case it benefits the entire team far more to play her at one of those two positions.
My current top player is IMHO a natural center fielder. I work her there and she plays there occasionally bit she also happens to be the best catcher on the team by a fairly large margin. Because it makes our entire team better when she catches, the bulk of her PT is spent behind the plate.
My best player is my best pitcher, catcher and CF. As much as I would love to have her in the OF when the second or third line pitcher is throwing, she is much more valuable behind the plate, when she isn't pitching.
What kind of hits does your pitching give up? If you've got a talented pitcher that rarely gives up a deep ball play her in the infield. If she's your only player that can get to the gap in the outfield and your pitcher gets hit deep then play her out there.