What is your recommendation?

I am a new Canon 30D owner and would like to add a teleconverter to my camera. Could you please tell me which one you would recommend? Thank you

What lens do you plan to add it to? That is the key.

Probably a Canon TC. Tamron and Kenko aren't bad either.

As Woolbur says, depends on what lens(es) you want to use it with.
I have a Sigma 70-200 and I would get the Sigma one, but if you had the Canon version you'd want the Canon.

I believe the kenko (pro?) ones are pretty good by all accounts, but just steer clear of the 2x ones (all makes), the IQ will suffer a lot more than with the 1.4x

just a point the canon tc's dont fit all lenses.
Rob.

I have a Canon 1.4 that I occasionally use on my 70-200. Well made and works fine.