Ishikei behind Tony Taka? For shame.
Now, I'm not saying Tony Taka is a bad artist. While Tony has contributed more besides hentai and doujinshi (anime, video games, etc), on a purely H stance, there are few among the same level as Ishikei. Ishikei still regularly does original hentai manga on monthly anthologies and does doujinshi as well. Tony Taka's doujinshi offerings have, since a long time now, been only illustration books whereas Ishikei's are usually actual stories.
Tony's style has a more 'cutesy' and 'moe' appeal to them as opposed to Ishikei's which gives a more erotic feel than Tony's work. Tony's cutesy and moe style is probably why he has been able to branch off to do things like design characters for video games among other non-hentai endeavors.
One great thing about Ishikei's style is that (probably with the help of his godly coloring) it looks fleshy. His females look like they have 'meat on them bones' for lack of a better term. Like Raparperi said, he can do small and large breasts in a way that looks natural. I can go on and on but people have said things I wanted to say. Lastly, he loves Kyou from Clannad and he like the series To Love-Ru. And that is a winner in my book.