From my observations and experience: If you started shooting with a Glock, stick with a Glock, your muscle memory in your wrist is developed for that grip angle. If you started shooting with anything else other than a P.08 Luger, go with the Sig, again your muscle memory has developed for the more conventional grip angle.
I started with anything else (the Glock hadn't been invented yet), but was forced to carry a Glock (still am), the Sig X5 was a small miracle for me.