i much prefer the ergonomics of the XDm over a Glock. feels much better in my hand than the Glock. now i can shoot a Glock decently, i still prefer my XDm over a Glock. as a general rule, the pistol that fits your hand the best, is usually the one you will shoot more accurately simply because you can control the recoil better.
i also have to agree with JonM, the XDm is an improvement over the XD platform. the XD is a good pistol, but the XDm is a much better pistol. match grade barrels, a better feeling trigger, interchangeable grip back straps, more streamlined slide and better sights.