Never shot an XD. But I've heard a few bad things about their reliability; probably only due to crazy gun nuts who sit on the computer all day nit picking. Can't beat the fact that the Smith is US made and it might even be a little cheaper. Plus, fewer external safeties = fewer things to break. IIRC the XD's had an issue with their thumb safeties, might wanna read up on that too.
Really? I've ran an XD45 for ~6 years, never had any issues with it, never a malfunction. Everyone I talk to in person and online shares the same opinion. They have been made in Croatia since 1999 and have always been very reliable guns. They were known as HS2000's before Springfield bought them. The grip safety is no problem, and is a very simple mechanism that has one moving part. It shouldn't break.
I hate the grip angle on Glocks but wanted a point and shoot striker fired gun, so the XD won it for me. The 13+1 of 45ACP is nice too. At the time those were my only 2 options, I would definitely consider the M&P now too. They are both on par with reliability so just put some rounds through both and get the one that fits your shooting style.