I have owned/used a PILE of product from both Blade-tech and Comp-tac. As already stated several times above, Comp-tac service is unbeatable. As for quality, it's coin toss. I feel like Comp-tac's mag pouches are quite a bit better than Blade-tech's but in the holster department, there's really no advantage of one over the other imho. The Blade-tech holsters can be a little more versatile, if you go with one that will accept multiple attachment configurations (SRB, DOH, tech-loc etc). But the Comp-tac product seems to utilize slightly better quality materials. It all boils down to what is most important to you and what best suits your personal needs.
As I type this, I'm wearing a Blade-tech holster and a Comp-tac mag pouch. You don't have to commit to just one brand.