If you like kydex, then talk to Gregg at Comp-Tac.com. I use a x-draw for my Ultra Carry when I'm driving any distances. It just slips onto the belt and away I go. The gun is held in place nicely with tension adjustment screws and "clicks" into place. For me its the perfect holster for this specialized application.
Alessi's DOJ is a superb rendition of Bruce Nelson's #1 Professional...a straight-drop holster that can be used strongside or crossdraw. www.rfholsters.com
The #55BN from Milt Sparks is another superb version of Nelson's classic. It can be had with a straight-drop, like Alessi's DOJ, or for dedicated cross-draw use, it can be ordered with a slight muzzle-forward rake. The Sparks "NLG" is a slightly modernized Nelson #1. It can be ordered straight-drop or muzzle-forward too. www.miltsparks.com
Mac10 is right on the money on the x-draw from Comp-Tac. You don't have to undo your belt to place or remove the holster. The gun stays securely holstered during the entire operation and can be quickly and discretely taken off if you need to leave it in the car for legal reasons. www.comp-tac.com