Check the results of matches that tell what everybody shot. You'll find a lot of Glocks, M&P's and CZ's. There is a reason why most people don't shoot something else. Also check Gunbroker for used gun prices. The above 3 still sell for a good price used if you decide to sell and switch. Other values doesn't hold up as well.
Are you going to share one pistol or buy 2. I would recommend they both be the same if you get 2.