Best tasting, most tender jerky?...

[Cruiser]

I like this, it's hard to find but you can order it from them:
http://www.minguabeefjerky.com/

This is my favorite!

[Ironbelly]

Make your own, its super easy. All you need is a box fan, some rope or bungee cords, and a paper air conditioning filter. Look up beef jerkey by alton brown on foodnetwork.com for a good recipie using this method. I use a dehydrator, but used the box fan method many times in the past. Making your own beef jerkey is so much cheaper than buying it premade.