Whenever I mid with Akali i use this build because of the high damage output. also, I don't need as much survivability if its only 1v1. whereas in side lanes, you're probably going to be focused. but, I do make up for the lack of defense with a generous offence and spell vamp.
a large amount of spell vamp combined with the burst potential of Akali is frightening.
You'll heal vast amounts of damage with just your Q. With the right sequence you're nearly
un-killable.

THIS BUILD IS NOT FOR THE PLAYER THAT IS NOT WILLING TO TAKE RISKS, OR FOR THE ONE THAT DOES'NT HAVE ENOUGH BALLS TO ENGAGE JAX ALONE. OR OLAF. OR MALPHITE. OR YI. OR ANYONE ELSE.

I WILL START OFF BY SAYING THIS BUILD IS NOT FOR NOOBS. YOU WILL SUCK IF YOU DONT KNOW HOW TO PLAY AKALI RIGHT AND CHOOSE THE RIGHT SITUATIONS TO ENGAGE.
The damage output on this build is considerably smaller until you get your stacks. but if you like playing snowball Akali, and you know how to survive a team fight and juke with your pool [W], then this is by far the best end game build. your attack damage is well above 300 and your ability power is 500+. That combined with Hextech Gunblade and you are just hella scury.
The survuvability on this build is a bit higher as well. with masteries and runes.

I HAVE tested and used these builds. i use them nearly every day whil playing Akali.
Please comment and vote!!!

check out my other 2 builds
CHO'GATH: Balls of steel.
and

Pubstomp MALPHITE