Twinnings is my usual. Pukka, mostly for herbies, and various supermarket ownbrands (not each of them’s cheapest ownbrand mind you). Yorkshire is decent, PG tips OK but I never buy the latter myself.

Guizhou Mao Jian (毛尖) of various brands is decent too, if you can find it. More commonly I love an English Breakfast, Earl and Lady Grey, Rooibos, and various herbal concoctions.

Edit: nicest brand of tea I had was TWG, and they were amazing. Too expensive for me to ever buy for myself, though.