I think the problem is that the question itself is flawed. The truth is... there is not a best option that can be decided for everyone. Everyone has different sized hands and have different perceptions. Therefore, there is no such thing as a "best" option in polymer pistols. When all of our hands are the exact same size, and we all have the same perceptions - then we can determine the "best" option.
Some people don't "like" the grip angle of the glock. Now they have Glock-like options with a different grip angle.
Some people don't like the trigger feel of the glock. Now they have Glock-like options with a different trigger type.
Some people don't like the appearance of the glock. Now they have Glock-like options with a different exterior appearance.
Some people don't like the plastic sights on the glock. Now they have Glock-like options with different factory sights.
--- All of these handguns are almost exactly the same in function and format, but the differences are there to meet differences in personal opinions and preferences.
I like the XD, M&P, and the Glock. They are all very good weapons. I would feel comfortable using any one of them. I happened to go with what I felt was the most proven, popular, basic design - which ended up being the Glock 19. I could have gone with the XD or the M&P and probably have been just as happy.
We as gun enthusiasts often get caught up in this silly "my gun is better" strain of thought - without realizing that the marketing campaigns have succeeded in brainwashing us.
The TRUTH is,
1. that all of these guns are excellent options,
2. that there is no such thing as the "best handgun b/c it is based on personal preference, and
3. even if you buy what you think is "perfect" - you will soon find a different "perfect/better" handgun and end up buying that one too.
Good luck on finding that elusive "best" one - because as we all know --- there can be only one!