Both are good, reliable guns IMO. The XD has the added feature of a grip safety in addition to the Glock-style trigger safety. The XD and the Glock have two different grip angles, the Glock grip angle takes some getting used to as it's not what I would consider to be "Point and Shoot".
My advice is to see which feels better in your hand and if possible, rent and shoot both and see which one works best for you.
I've had my XD9 since 2004 and absolutely love it. I'd say handle them both and see what you like.
"They're on our right, they're on our left, they're in front of us, they're behind us; they can't get away from us this time."
Chesty Puller, USMC, Chosin Reservoir, Korean War
"You cannot exaggerate about the Marines. They are convinced to the point of arrogance, that they are the most ferocious fighters on earth - and the amusing thing about it is that they are."
- Father Kevin Keaney, 1st MarDiv Chaplain, Korean War
For me the SA has a much better feel, translate, grip angle. Also the SA supports the case clear to the back, Glock does not and the cases bulge. This is important mostly if you reload. It also seems to me to be a safety issue but apparently not since I have not heard a single complaint about a case blowing out in a Glock.
I'm also considering one... a group of us went to the local range and I rented one... plus got to try out everyone else's stuff. Being a novice and quite new to guns I was doing OK with it... 95%+ of shots hitting the target. One of the other guys I was with tried it and, having never shot it before, put 10 shots in about a 3" circle at 7 yards.
shot both, and now own an XDM9 compact. Glock grip angle is just strange to me, the XD and XD(m) is closer to a 1911 type grip. plus the grip safety on the XD(m) is a huge perk to me, having that second safety that doesn't require remembering to turn on or off is great.