Just to include the last two seasons of numbers:
Fleury: 42 wins, 2.36, .913
Miller: 31 wins, 2.54, .916
Fleury: 36 wins, 2.32, .916
Miller: 34 wins, 2.59, .916
It's close, especially if you feel Miller will bounce back. I also wonder how much Vokoun will eat into his starts, reducing the number of wins. Both have had inconsistent years - Miller's GAA has been north of 2.50 in all but one season, but lately has been better in SV%. Fleury's had some good seasons but some bad ones as well, and usually a worse SV%.
I'd lean towards Miller by a hair, just under the assumption that he's bound to improve with an improving team, and that Fleury can't go much better than his last two seasons with Vokoun right behind him. Close one.
All I've got...all I've got is insane!