This is a pic by Iwasaki Tatsuya I colored. I really like Tatsuya-san's art style, he did a comic called "Monsterlog" that I loved when I was younger. If there was an English version, I would probably color it, too. His style is very unique, which may make it less palatable for some but it's what draws me to his work. Hopefully I'll get the opportunity to color his work again.
As for the picture itself, I've always been fond of Mai. I like that hairstyle, which is why I'm also pretty fond of Chi-Chi and Twilight Sparkle (among others). There's a really good comic featuring Mai I would like to color someday, but unfortunately it can take some time to work through a whole comic.