As military we get sweet deals from Glock, smith etc..... as such I bought quite a few Glocks and Smith/Walther guns.
The M-9 does suck. I have a few because CDNN had them dirt cheap, but otherwise, in combat it stays strapped to my leg and will probably never be used. and the M-9 has a manual safety, not good for 4am stumbles with somebody in your backyard.
I love my SIG 9mms (228/229, stay away from polymer sigs). They are the heat, BUT......they are metal and rust. They are so beautiful that I just dont want that to happen to them, so in the safe they stay. If you can afford a Sig, get one.
The SW99/waltherP99 if I read correctly, stay away from it. My P99 felt great but shot like hell. the Trigger sucks. The SP22 trigger is the worst in all mankind, another walther F-up.
The M&P is a trusty pistol, we bought them for Afghansitan and Glocks for Iraq, that says durability. The M&P is a little tall though, compare both pistols side by side.
I went with several glock 9mms instead of an M&P because its a lower slide picture and felt better. I have several G-19s and several G-26s. The advantage is that lighter trigger springs and mods are cheap and sold everywhere. The lighter pull makes groups a lot tigther and shooting a lot more fun (target, not law enforcement).
I hated Glocks until I fired one with a 3LB trigger. After that I put my SIG away and use Glock at the range. And it wont rust, if I drop it, its not a SIG so I dont mind scratches and its plastic so I can hose the thing down if it sits in my dirty pocket too long.
If you are going to get a pistol, get the TLR-1or 3 flashlight and nightsights, better to buy them already ON the gun vs adding them later.
Streamlight TLR1 Weapon Light IN STOCK and ready to ship!