Readers of Megami Magazine, a magazine providing amazing amount of ecchi stuff to their readers, have voted for their favorite characters in the character popularity rankings. The results are as follows.
1. Akiyama Mio - mai waifu
2. Fate Testarossa - mai main waifu
3. Hirasawa Yui - she was getting on my nerves sometimes
4. Katsura Hinagiku - mai tsundere waifu
5. Haramura Nodoka - haven't watched Saki yet
6. Takamachi Nanoha - the White Devil, too scared of her to make her mai waifu XD
7. Horo - the Wise Wolf, don't wanna get eaten
8. Sakurano Kurimu - I haven't made an opinion on her yet
9. Misaka Mikoto - Biribiri, I don't like electric shocks in particular, though sometimes they may be hot
10. Senjougahara Hitagi - stapler waifu
What can we tell from these results. Well, characters with big oppai are quite on par with not well developed characters. There's a lot of loli, moeblob characters such as Yui, Kurimu, or Nodoka. However, more mature looking characters are present as well, i.e. Horo, or Hitagi.
I approve of this list. Though, my top 10 would probably be a bit different. I miss there for example any characters from Clannad. And I would have to include Alice from ARIA as well as some other characters. But that would make it at least a top 20 instead of top 10. Yes, everything is very difficult when you aim for the harem ending.
Sankaku Complex
