Thoughts on Kenko and other teleconverters
 

This may belong in some general lens forum or something, but I'm sure you guys have some.
So I don't feel like buying any more huge lenses (only really got one, but anyway). Can't be bothered carrying them, can't afford them. A teleconverter seems like a fun option.
Since most of my EF lenses are third party it seems genuine Canon TCs are out, if I understand it right.
So how good are the other brands and their models? Kenko seems like an ok option. I'm not really fussed about AF. But how are they at 2x and 3x with third party lenses and so on? Any other brands I should know about?

cheers