I'm convinced .... NO ONE knows what "flat" sounds like. I listened to dozens of speakers taht are advertised as "flat" and they each have their own particular sound. Best thing to do is listen to something that is VERY familiar to you .... bring it to the stores, and listen to THAT material on each set of monitors. Buy the one that sounds the best for THAT material.
I happen to love the sound of these yamaha MSP5's but I prefer using the Non powered approach so I can listen to what the general public will use. My Sony 100watt stereo is my mixdown amp and I use Event 2020's as the main speakers.

Buy what sounds right .... forget the ads and the recommendations. use your ears .... and ONLY your ears.