Both Mountain Rose Herb's red and green are quite good, though I can't testify as to whether they're better than the others. I feel like the playing field is pretty even for rooibos, but MRH has good prices (and they're organic).
I've ordered stuff from MRH (mostly not tea) a few times now and I'm really happy with them. Their peppermint is quite inexpensive and super fragrant if you like peppermint tea, and I just got some lavender flowers from them. It produces a really fragrant tisane that smells like you're about to drink a cup of perfume, but has a pleasant and less in-your-face taste. I feel like I'm advertising for them.
I've just been happy with them so far.