I think most of the people like this one, because it's pure, innocent, no arms (even pacifists have to like this ) bright & optimistic and of course it's an angel... I don't think she's that naked to be the main reason for being favorite... if you know what I mean She's fabulous! The backlight does a lot magic...
What got my attention is the grace in the form and the colors used. I will agree with you that some of your other pieces are better in detail, color/contrast, and balance. But don't knock this one down too much. I don't know the work you put into it, but there is a lot of good here. The incense burners which makes her the fulcrum of a scale is an especially nice touch that harks back to the old school magic, before they started blending the colors into the madness we see today.
Hot mostly-naked chicks may sell, but *good paintings* of hot mostly-naked chicks probably sell better.
Seriously though, it's probably several things. For one, the composition is very simple, and reads well at card size. Plus, it's a splashy rare, plus many people like angels just because.
In addition to all that, Magic's actually pretty good at avoiding cheesecake and fan service in general (which is a good thing, IMO), which means that the occasional mostly-naked chick tends to stand out. Also not a bad thing.
Anyway, at this point I'm rambling, but you can count me in the *randomly like this art* crowd.
To be honest i love this card a lot, the illustration and the effect that the card has are awesome, but i don't like the hair, while i'm viewing the rest of the artwork the hair doesn't look like belongs to her. Anyway i love the artwork.
Personally I collect Angel Cards... I wasn't a big fan of the last bunch with the Halo's Blinding them to their sin or whatever... this was a wonderful reprieve from that not mention some angels just have a way of looking butch... it was nice to see the return of a really feminine angel.