i once have both, and I kept comparing the two drones while I got hold of both of them.
many reasons are discussed above, but as some members questioned why people say MP is just slightly bigger than
MA, as one of those who think alike I think it would be good to say a few words in this area. The main point for me is that the MP is already small enough to fit in any of my backpacks / camera bags with me to go anywhere together with my other gears.
MA is really smaller, but that is not a big difference to me, after all you still need to carry the batteries and/or car chargers and/or your IPad/phone. I have the MP Fly More Combo, which gives me more than an hour of flight time. If
MA needs the same flight time, you may need 5 batteries, which required more space in return. I don't aim at trashing the
MA, I am just saying the MP is really not bulky even compared to the
MA.
For video quality, I doubted whether
MA really has a better MP in practice.
MA got 4K 100mbps for sure, but practically I really can't see much difference for layman eyes (and especially if you aim at putting on YouTube only). And I experience myself, as well as watching from YouTube that
MA infinity-focus lens is softer than MP when MP focus well.
My video quality comparison between the 2 drones can be seen here -
The most important reason for me to choose MP over
MA is the reliability of Ocusync - this is the BEST SAFETY MEASURE to me, plus personally I don't have much chance using the front/back sensors (my total flight distance is about 200km) myself.
This is my case, but I do believe everyone got different needs and preference, you will find joy flying any of them.