I’m not going to vote in the poll, as person-to-gun fit is so variable. But I have a Glock 34, and and XD45 “Tactical” (very similar to it’s 9mm brother), and I’ll give you my thoughts based upon my experience spanning several thousand round with each:
1) Hand Fit: I have smaller than average hands, and the G34 feels just a bit awkward and blocky to me. If you have larger hands, it might feel perfect. The XD fits me very well. As far as the much argued grip angle is concerned, I have shot both enough that muscle memory seems to put either on target equally well.
2) Trigger: I might be in the minority here, but I find the STOCK G34 trigger better than the XD. The Glock trigger, while “sproingy”, is reasonably light (too light for carry duty in my opinion) and consistent. My XD’s stock trigger was long and mushy with more overtravel. I’ve since had a trigger job performed on it, and it’s real nice (although not at all like a nice 1911 pull). I actually wish I hadn’t had such a light pull weight set (it’s under 3 lbs). It’s somewhat like a button-switch now.
3) Reliability: Both have been very reliable. My XD45 doesn’t feed semi-wadcutters well, probably wouldn't be a concern w/ the 9mm, but hasn’t ever had a problem with roundnose and HP’s. My G34 hasn’t been 100% with factory ammo, but I’m not sure that wasn’t the ammo’s fault. It’s last 4000 round or so, mostly my hand loads, have been flawless.
4) Sights: The G34 comes with adjustable sights, but they are very large, plastic, and the adjustment increments are pretty large. I think I preferred the fixed stock XD sights (although I have Dawson precision adjustable now) to the Glock’s.
5) Practical Accuracy: As I have an XD45 vs. an XD-9, I can’t vouch for the XD-9. But slow-fire unsupported at 25 yards, I tend to shoot significantly smaller groups with the XD, even before the trigger job. At 50 feet and closer, the difference is not as significant. At 10 yards I can see no difference in practical accuracy for the most part. For whatever reason, I am more “streakish” with the Glock - sometimes it’s one-hole city all rapid-fire-like and sometimes they’re flying out of the black while I‘m really concentrating. Can’t figure it out.
6) Features/Safety: For the most part a toss-up, although generally argued in the favor of the XD. I find the XD’s grip safety 100% unobtrusive, however. My XD’s loaded chamber indicator sticks open every couple of thousand rounds and requires removal and cleaning of the recess (easy enough). Both are very easy to field strip.
7) Finish: Glock all the way here. The finish isn’t pretty, but it’s hard to hurt.
If your set on a poly pistol, I don’t think you would go wrong with either (haven’t shot the M&P much).