A glock 19 or M&P would be a great choice. They are some of the best guns on the market and if you ever decide to sell they have good resale.
I'll admit I'm a bit of a gun snob. When it comes to something that I'll be trusting my life to I don't mess around. I like to find out what professional instructors/shooters/ industry professionals and other respected experts on the subject have to say. That said, and while trying my best not to bash, glock and M&P are the most respected and most recommended. It is worth noting that generally when one of these "experts" is asked about a gun that they have not endorsed they generally just say that they haven't had enough experience with them to say one way or the other. Since those guns are not too far apart in price AFAIK I just figure I might as well buy the one that is the most proven.
Personally, I really dislike safety features that I don't feel are necessary, and the SR9 is loaded with them. For me the mag disconnect, internal key lock, and manual safety on a striker-fired pistol are just things that complicate the gun and could possibly fail. I haven't heard of it happening on the SR line but I'd rather not have them. I'm also not a fan on the grip safety of the XD line. Again this is my personal opinion, YMMV.
I don't collect guns, I accumulate them.