I am yet to try any commercial rubs as I (and many others) am very happy with the rubs I make myself, so why not make your own? It'll be far cheaper in the long run, and you can tweak each rub to suit your individual needs/taste.
With a few basic ingredients, you can easily create a variety of different rubs to suit everything from chicken, beef, pork or even fish.
With a little Googleing I'm sure you can find a few good rub recipes to make a start.
If you're still uncertain on making your own, hopefully someone will reply with a rub you can buy.
Best of luck,
SR.