I find myself often looking for something to replace my Glocks, but I am never able to match my Glock performance with anything else. By policy at work (LE), I will not ever get away from Glocks completely, but the more I branch out the more I find that I shoot Glocks best. Currently my duty G34 is also my competition pistol. I've got an SP-01 that I hope one day fills that role, and I shoot it well, but the Glock is still king. I bought a CZ P-09 thinking it may be "the one" but it fell woefully short of my Glock performance in the first match I used it in. I'm ordering a short reset trigger kit for it, but I still don't know that it will dethrone the 34.
For me it comes down to ergonomics and better hits, faster. I have a huge time/ experience bias towards the Glocks, but they just seem to do it best for me. My next attempt will be the Steyr L series, which may have the best chance of all, since it seems to be a refined Glock. What sucks with it is the lack of aftermarket support, particularly when it comes to sights.
I tried an M&P and the perceived muzzle flip compared to my Glock was a major issue. No matter which back strap I tried, nothing fit me when shooting even though they pretty much all felt better in the hand. Then NOTHING about the VP-9 appealed to me. And most recently I've shot a Sig P320 a little bit and it seems to be ho hum for me at best.