I have both a Glock 19 and Springfield Armory XD9. Essentially, that's your two choices, only in 9mm rather than .40 S&W. To me, the Glock is a little lighter and thus carries better. The Glock also has a lower bore axis and seems to have a bit less muzzle flip. Conversely, the Springfield feels better in my hand and has a grip safety if that makes you more comfortable. On stock guns, I think the XD sights are better than the Glock's. That's a non-issue if the Glock you're considering already has night sights. At bottom, I tend to like my Glock slightly more than the XD, but not by much. The price you're seeing for the XD is about right, but it's hard to get a Glock and three mags under $400 without a LEO discount. If that also includes night sights, that's an absolute steal that I wouldn't turn down.