The XD is the better gun as that is what I bought. I started with an HS/2000 back in the late 1990s and have kept pace with them as they morphed into the XD. Over that time I have become fairly familiar with the XDs and have become familiar with whatever quirks they may have. After 2 HS/2000s and 6 XDs, I have had quite a chance to become familiar with them.
Then again, if the M&P would have been around back then, I might have had a different opinion.
Either gun is a very good choice and I would have to say that one could not go wrong with either. Pick the one that calls to you the most and don't look back. Instead, look forward to the day you buy the other one.