That really comes down to personal preference and does the pistol fit your hand. Spec wise they are both very much alike; size, weight and capacity.
If anything, it might come down to price as the Beretta is much cheaper than the Sig.
I don't think you could go wrong with either.
The Sig actually outperformed the Beretta during the Military Trails slightly. ...
That's right. Refresh my memory. We wanted to locate some missiles in Italy or something at the time didn't we?
LOL...
I usually go with what fits my hand the best. If possible, shoot both before deciding.