I guess your not really on a dollar range. I might be wrong but isnt the USP about $200 more then the GLOCK/XD-40. If you are looking at guns in the $750.00 dollar range, look some Sigs. or even a Springfield 1911.
I was only 21 a few years ago, Im 24 now. I remember when I was able to get my first handgun under my name. I went out the day I turned 21 and bought a pistol. It was not my first pistol though. I had them for years.They were just under my dads name and when I turned 21 he came to my house and gave them all to me. So, point is I had 12+ year exp. with hand gun shooting befor I was 21.
Evey gun you named is a great gun. I own every thing you named but a XD-40. But, you really do not know if you trully like a gun by the feel. I would find a range and see who has them to rent. You really need to shoot them, at lest 200 rounds though each one. I mean, you might find the one that feels the best on the show room floor, feels like crap when it goes bang.
I do not know if you carry at all, but most of us on this forum do. If you do while your at the gun shop, put them in a holster where you will carry the most on your body and see how if feels, draws, ext. ext. .
I would also think about parts and custom stuff. You might end up playing with trigger pulls, sights, springs, more MAGS. ext. ext. . You also might want to get into some type of shooting team, so, you might want to look into what is and is not aloud.
If you are hell bent on a .357Sig. Get a Sig. or Glock, IMHO they are the best .357Sig. shooters.
But, I would not buy any thing till I shot it. I would shoot shoot thoughs guns first.
These are only MHOs.
Good luck.
Dave.