I have large hands and the USP45's blocky and more aggressive grip gives me a better purchase and hold than the HK45's batman sandpaper like grip.
When I do rapid fire drills, the USP45 sticks like glue in my hands. The HK45, not so much, as it tends to slip...
HK45 All the way!
The only thing better than a USP45 is a USP45 Tactical.
I had the same question a few weeks ago and I was trying to choose between the two. I went with a USP45 Tactical. It’s not as slim and I’ll need an adapter for attachments but I can live with that.