When I was deciding between polymer pistols I was looking at Glocks, M&Ps, Beretta PX4, Ruger SR-9, and CZ SP-01 Phantom/Shadow.
Don't like Glocks, never have, never will. Never liked the looks and don't like the grips. Don't get me wrong, Glocks are great guns and have nice triggers, but they're not for me... nor will they ever be.
I like M&Ps, really like the ergonomics of the grips and controls, nice sights, kinda nice looking (ugly you can fall for kinda deal, eh), and cheap! Biggest downside, hate the trigger. Most of the research I did on the M&P showed most people were getting trigger kits right off the bat. So, the dollar price just went up almost $100. Still would like one one day.
Beretta PX4, really like it. Fits well in the hands, trigger is decent, unique looking, shot well. Downside, very hard to find up here and more expensive than it should be.
Ruger SR-9, great price! Grip was a little thin for me, trigger felt very, very stagey, but I hear it gets better with time.
CZ? Felt awesome in the hands, great sites, nice trigger... But, it was heavy and I didn't feel like dropping $800+ tax for it.
XDM, great price and value! Felt great in the hands, trigger was different but I could work with it, sights lined up very nicely, also you don't see them a lot up here so I kinda wanted to be a little different. I used to hate the look of the XDs, but I love the look of the XDM... weird innit? Did I mention the value?! Big case, holster, mag pouches, mag loader? Not too shabby for added value. Lots of XDM aftermarket parts out there too, so that helped me make up my mind. Other great features, that don't really apply to us up here in Canuckistan, 19 round factory magazine??! I really like my XDM.
That being said, just like all firearm purchases it comes down to your personal preference. Does it fit well for you? Does it meet your wants and needs? Do you like it's overall and potential value? Every firearm has people who love it and people who really really hate it. Hell, I know people who hate 1911s! Not really friends with them anymore, mind.