I tried Takashi's (aka 2geeks) sapphire crystal for my Pre-As and am quite please with the result. Not forgetting to mention that his asking price is rather reasonable.
Here's the pic ...
For 44mm crystal, I think Takashi's crystal is recommended.
CASE: JF, 111J, EL, Old Helenarou, Jackson Tse, Getat, DSN
DIAL: FGD, DSN
HANDS: FGD, DSN
CRYSTAL: BigCrown, Takashi (aka 2geeks), DSN
CG: LH, TB/WSO, DSN
CROWN: T48, PALP
CASEBACK:Jakob, DSN
BUCKLES: Rolexfinder
STRAPS: Frogman, MMX