I know this is somewhat controversial but I prefer Mega Evolution over Regional Variants. Please allow me to explain. A lot of the regional variants are simple recolors of the standard form we've come to know with a few tweaks here and there. Instead of recoloring old mons why not invest that time designing new mons? Not only that but some even stand to outshine their standard counterparts, essentially the original form gets nothing new but its new cousin on the block does? It kind of annoys me. If your going to make a regional variant at least give the original mon something new to play with. I know megas weren't perfect and could've used a bit more polishing, but it put forth a lot of unappreciated mons like Mawile (my favorite Mega Evolution btw) and made people think of them again. And yes I acknowledge that most of the megas could've been their own standard evolutions (Mawile for example) but at least they gave something new to otherwise forgotten Pokemon.