Which Glock 21 did you try? I could never get into the 3rd gen Glocks... even the SF... but the Gen 4 Glock 21 feels perfect to me. I love it.
Other than that, the XD 45 has a pretty comfortable grip. XDM 45 is worth checking out. The FN 45 is a great option as well...
The Gen4 Glock 21 is definitely my choice though... and I say that having bought and sold an original Gen3 and a Gen 3 SF Glock 21...
I've had the Gen 4 for a year now and have a couple thousand rounds through it. Absolutely great gun... soft shooting too.
Glock 17 OD | Glock 19 G4 | Glock 21 G4 | Glock 20 G4 | Springfield TRP Black | Smith & Wesson M&P 9 Pro | Smith & Wesson M&P 22
Daniel Defense DDM4 V4 | Arsenal SGL 21 | ASA SBR w/ Side Charger | Mega/PSA M4 Clone | Remington 700 SPS Tactical | Savage Mark II FV-SR
Mossberg 590A1 | Mossberg 500 Cruiser w/ 590 14" front end | Remington 870 Tactical