Try the good qualities of Oolongs, like Shui Hsien, Tieh Guan Yin or Da Hong Pao, once you get used to Oolong you're likely to become addicted. These are not brands but varieties: if you really want to taste teas, do not use teabags but a teapot (tea leaves need to unfold to liberate their flavour). Moreover, teabags are really expensive compared to loose tea (according I understand what you mean by "loose tea", my english is everything you want but perfect), you're likely to pay double price for the same quality.

Other interesting teas: northern Iran (yes, they grow Camelia sinensis in Iran), unbitter rich black tea, spring darjeelings and Imperial Pu'er -pure delight. Tea in China and Taiwan is much like wine in France: they have hundreds of "brands" each one having it's own personnality. For the price of twenty average teabags (fifty grams) you can get one hundred grams of very nice tea.

Yerba Mate is not tea, but a south american bush (Ilex paraguaiensis, if you want to know): it's a bit bitter when you taste it first, but you easily get used to it, I wakes you up faster than coffee and is harmless for the guts!

And never trust a brit about tea, tea is just and ersatz for coffee in England

Edit: Pannonian, you've just "cut the lawn under my feet"