Tetley British Blend is a good value, authentic British style tea available in Walmart, Target, Grocery stores etc.
Tetley also have a green and black tea - I think it's earl grey - which I like occasionally. I think they got the idea of a green and black mix from Stash whose version is better.
Otherwise, I rotate between Assam, Ceylon, sometimes Kenyan, and "Gold" teas which are a blend of those three. Yorkshire Gold is one example. Kenyan and Gold teas (which have Kenyan as part of the blend), are good when you want something more robust in flavor.
When brewed correctly, Darjeeling is an amazing tea. I can imagine many people not giving it a second chance because brewed incorrectly it ends up bitter and loses it's subtlety.
White tea is also very nice.
I don't drink green teas as often as I maybe should, as the health benefits are greater. When I do, I like Jasmine tea.