I have two different tea categories. A normal cuppa or brew serves a very differs purpose to 'fancy' tea. So I have two answers.
For a cuppa my go-to is 1 bag of twinings english breakfast and 1 bag of twinings earl grey made in a teapot. Its kind of just what I really associate with that kind of tea as it is how my mother made it when I was young. I'll happily throw a bag of Yorkshire tea in a mug but its not my favourite way of doing it.
Fancy tea... I very much came down on green teas as my favourite but lighter oolongs and sheng (raw) pu erhs are up there too. I'd be hard pushed for a firm favourite but I have a wonderfully sweet and creamy gyokuro karigane japanese 'twig' tea and a chinese 'yun wu ming qian cloud mist' that was light, sweet and utterly delicious.
I go for a cuppa as a caffeine hit or just something nice in the morning or a drink when doing stuff but a fancy tea during the day as something a little more ritualistic as a nice break from work.
I got really, really into it. I get a monthly subscription box with 4 uncommon and expensive teas, 2 light and 2 dark per box. I have a whole tea battle station in my living room (my mother's ercol cabinet that no longer fits in her house) with all the tea and excess equipment inside and tea making facilities on top!