Shishui ka is definitely alone one of the top jutsus that puts him in top 10. My top 10 edo madara/hashi,tobi,nagato,naruto,minato,2nd mizu/muu,danzo/shishui,3rd raikage,sasuke,bee
First of all, that is not a top 10, that is a top 13.
Secondly, most people do not like to count KA, because it's technically an auto win. It doesn't require eye contact and the enemy is unknowingly put under a genjutsu. So if you look at it THAT way, technically Shisui SHOULD be the number 1. But even you can agree that that is not the case.
That's your "Top 10" which means your opinion. Feat-wise, Shisui has nothing that could say he could fight toe-to-toe with many other "Power-houses" such as Tobi, Madara, Naruto/Sasuke, Nagato/Pain etc. The only hype he has is the powerful Genjutsu KA and/or Body Flicker Technique which has less chances of getting him anywhere in battle or in multiply situations/scenarios (E.g. Vs. Threads). We simply do not know to much about him.