I have and carry a Springfield XD45C and love it, it's my favorite firearm to-date. The Springfield XD9's had a roll-ping breakage issue so make sure you get a late 2010 or 2011 manufactured gun if you decide on it. Very reliable gun, one of the only models to have zero failures of any kind on the 2000 round torture tests.
The Glock is the standard by which all guns are judged these days but the grips are just a bit too uncomfortable for my liking, they just don't fit naturally and I don't get instant sight alignment like I do on the XD. Also a very reliable gun and had only a magazine related failure to fire on the 2000 round torture tests.
The Ruger is getting good reviews these days but I purchased one, had several FTFs within 300 rounds, swapped it for another and had more FTFs. I personally just can't trust a gun I intent to carry to possible save my life when it fails to fire so many times while breaking it in. Other people haven't had these issues, just my experiences.
My vote is the XD as long as it's a newer model, and the Compact series which comes with an extended magazine is very nice for target shooting.