gen4 g19 is the way to go, nice sticky texture grip and with nightsights you have a good sight picture, gun you can work on yourself, lots of parts available, lots of sight tool and variety of sights available.
factory magazines are easy to find, and inexpensive.... lots of holster choices and conventional controls.
having owned the p2000, and currently owning all of the 9mm glocks (G17L,G17 Gen3, G17 Gen4, G34 Gen4, G19 Gen2, G26 Gen4 + G21 Gen4, G21SF Gen3) I am a BIG glock fan so my advice may vary....
the one thing that irked me with both the P2000 and the USP was the paddle style magazine release, shooting *DPA it was always a bit of a struggle to release the magazine and yet at other times it would seem to get pushed down on it own, but each to thier own and you have to try it to get the feel for it.... me I would rather push a button then have to push down on the paddle. (as an aside the USP and P2000 are ambi all the time)
now one of the great things for the gen4 glocks is the adjustable backstraps, frankly I use mine without any backstrap.... but also the magazine release is enlarged and ambi so you can put it on either side (as long as you use gen4 mags).
my money would be on the glock... but you have to try both
