USP-S
Pros: It's popular (not really a pro but it is something to note), it is a bit silent
Cons: Only 2 extra magazines to spare and a smaller magazine too
P2000
Pros: Larger magazine, higher accurate range
Cons: Not as popular as the USP-S
Other things to note:
The USP-S and P2000 are the same in every aspect except noise level, magazine, and accurate range