It depends on my mood. Lapsang souchong or ginseng oolong are among my favorites. For herbal tea, dry desert lime by Numi, though it's expensive, and I'm not going to order any more for a while. Generally speaking, I go for variety. If it's within my budget, I try it.
For herbal tea, getting dried hibiscus in bulk is a great option. You can find it at Mexican grocery stores