You can't go wrong with either the Sig or HK. Both are excellent gun makers. THey do, however, differ greatly in their triggers and control placements.
Rent them both, shoot, shoot, and then you'll have your answer. Dollars to donuts, you'll shoot better with one and that particular gun will fit your hand better, aim better, and cycle better.
Whichever gun that is, buy it. (In my case, it was the HK. Plus we carry the HK USP40c in the cockpit with us so that was a bonus!)