The Kenko set is a good choice, you don't want a cheap one with a plastic mount. Keep in mind that tubes work better with shorter focal length lenses. Depending on what you're shooting, the working distance with extension tubes may be too short, compared to a true macro lens.
Personally, I have a Canon EF 25 II tube, bought used for a great price. I trust the mount strength of the Canon more than a 3rd party tube, but that's a personal decision - I don't really use it for macro, but rather to shorten the MFD for a supertele lens - with an 9-lb lens, mount strength is a key factor for me.