I have owned 3 XDs in 45, I traded or sold them all.. I have owned Two Glock 21s, and I still have one of the two.
I originally carried a Glock 21. I Got the XD to see if it could replace the G21.
I liked the XD because of the grip angle and the comfortable grip. I didn't like the XD because of the trigger reset and the fact that I couldn't completely disassemble the pistol without knocking out roll pins. I got a XD tactical with intentions of sending it off to get a trigger job, but that fell through when money got tight. After a while, I decided to go back to my G21. Soon after that, the G21SF came out. I started hunting one in area shops so I could compare it to my G21. After about 2 months, a gun shop got one in and I was able to compare it. I had the G21SF(ambi) in my hand for about 10 seconds , then I told them that I would take it. I sold my G21 and I still have the G21SF.
I prefer the Glock over the XD because : I have more experience with the Glock system, the Glock system is K.I.S.S. simple, I know how to fully disassemble the glock and repair it (if needed) without serious tools, I can buy $30 worth of parts and have an excellent trigger on the Glock ( vs $80-$120 for the trigger kits for the XD).
Most of my reasons for choosing glock are of MY own preference, YMMV. I did not have any trouble with the XDs that I owned, they just couldn't deliver like my Glock could. I did have a grip reduction done on my G21SF to get rid of the grip hump, which turned out to be well worth the money.