Twinings for me; Darjeeling and Assam. They are similar in flavour, but different ends of the strength scale. Lapsang suchong for a change, every now and then, to mix up the tastes. There are some green teas I like such as Jasmine, but is for when I am eating something mildly spicy. I have recently returned to tea, after many years of drinking only coffee. As one advances in years, the affects of the caffeine become more pronounced. I like my coffee strong and black so it was becoming a bit wearisome. I haven't given up coffee, I just drink a lot less of it now. As I drink my tea black as well, so I filter my water through a declac filter, to avoid the scum build up on the drink. It gives a much cleaner flavour and clearer hue.
I use both loose and bags. Bags if I am making just one cup and loose if I am making a pot. I use a diffuser for the larger pot and a I have a built in mesh filter in the smaller one. If Darjeeling or Assam is left in the pot for too long, it becomes over brewed and eventually develops that scum and leaves a bitter taste.