mATX this mATX that, just get ATX and solve all your troubles. Losing a couple slots doesn't make the case magically half the size or portable.
The useful features on motherboards have been steadily declining and being replaced by RGB cancer. While top priced products are now what mid tier used to be.
5 phase what? 8 phase? Come on, even my mid tier cheapo Intel board for Z97 has 12 phases, sure 6*2 doubled but what ever for a 4 core it pushes anything one throws at it. Sadly one of the last boards to have good VRM, good audio, good LAN, extra USB3, extra SATA ports, dual UEFI chips with switch while not costing a fortune.
Modern boards be it for Intel or AMD, no difference, are cost cut, replacing useful $5 features with $0.5 worth of LEDs.
Sadly there is no clear cut winner to buy, what board has good features, price and quality changes with each launch. Sometimes it's brand A sometimes it's brand B, C, D, ...
ASRock has grown and they too started to cut down features replacing them with RGB.
Reviews for motherboards are important nowadays more than before. CPUs getting power hungry and boards weak.