Those are the gold standard for covers...great lighting, the theme is clearly reflected, they show their entire body with enough skin to whet your appetite, and it isn't too clumped with words.
I also enjoyed the "High Handed Female Teacher" series. It's satisfying because they start out authoritative and abusive, only to be taken to task. Nanako Mori's one stands out, she slaps her students lol.
I don't know about the rest of you, but I never had teachers who looked like that! Waha! school would have been a lot more exciting!
Two more gems i forgot about
STAR-524