Levi's!
When my oldest boys were in the thick of wearing out their jeans in the knees, I had the best luck with Levi's and it doesn't hurt to iron on a patch on the (inside!) knee area when you first buy them. If you wanted to go cheaper b/c Levi's are a bit spendy ($26-$42, I just bought a bunch at JcPenny's) I like the Mossimo Jeans at Target...they are sturdy and cute!
~I suggest getting the softest fabric patches you can find and then iron them in and then wash them (maybe even a couple times?) b/c sometimes I have noticed that the outline of the patch can be seen from the outside, which I didn't really like. The darker the color Jeans the less noticeable the patch is from the outside too, just FYI! I think the outline of a patch is a lot better than a hole though!
I have even been known to find a 'cool' looking patch or two from Michael's Craft store and sewing it on the outside (with matching cool colored thread) of a couple of my favorite pairs of my boys jeans, when my only other option was to toss them or make them into shorts
Good news is, I have found that the hole-in-the-knee phase only lasts from about 4-5ish through 11-12ish...so a mere 8 years, Ha!
No brand is immune to a rough and tumble active boy...no brand that I have found anyway! Gotta love them boys!!!
Mom/Auntie to 6 boys!