Any favorite types, or brands, or vendors?

I’m a fan of What-Cha.com, but they’re in the UK so I have to wait until it makes sense to do that international shipping. kuchata.com is in Denver and closer, but I also like Harney and Sons and Adagio Teas.

If you can, try a local international market. No matter what region of the world the stock is from they will likely have a tea aisle with loose leaf in it.
I’ve done that a few times, but the ones I’ve encountered have tended towards black breakfast assam tea types, and I like the lighter blacks and oolongs better. I’m sensitive to bitter tastes.