The one that makes the most sense is you lose that place for a slide-out. Leaving you to a single slide in the front of the coach. Ours has two opposing slides of the same length which makes a huge living area. With a mid door that won't happen.
Most coaches have a awning that can be put out over that door at the front leaving no more that a couple of feet before being under the main. Having a side side door being a advantage for that, it didn't matter to us. It was all about the real estate inside.
Front doors makes for a much more useable square footage and allows for better slide out posistioning