You know...I did not even piece that together :lolHe isn't asking for the subjective "best ninja ever"...1985 through 2015
he is asking "best ninja ever from 09-12" where they are all identical--so the answer is all and none at the same time...the only thing that has changed is paint really.
To add to the above.05/06 - Common MC issue, easy repair...$50 in OEM parts to rebuild your front MC
07/08 - Common Valve Cover Gasket leak...easy fix as its a recall and should be free at your local stealership
09-12 - Common Regulator/Rectifier issue...also a recall so if your bike falls under that should be free
This ^Well if you are only looking 09-12........... they are all the same sans paint scheme
The only bolts I have had problems with (2 of them) were because they had too strong of Loctite used on them and/or they were installed too tightly.All identical 09-12. Like the other guys said. Very razors edge bikes. Well built though with som oddities. The oil filter is put in a place to unavoidably piss on your motor when changed. The oil drain pees inside the fairing if you change oil on the kickstand instead if stands. A lot of the allen head bolts use small allen key sizes and weak metal so they strip after a few uses. About all ive run into sofar.