Mug, definitely. But not just any mug! Oh, and infuser
This will sound like heresy to some, but.
The best drinking vessel for my tea BY FAR that I've ever had is a 12oz (350ml) "Easygrip" insulated PLASTIC mug from Aladdin. Bought for me (as a joke, mind you) by my wife one Christmas. Best "joke" ever - with the spill-free lid removed, it is incredible. The lip shape is, in some indefinable way, absolutely perfect to drink from, whilst the tea is still beautifully hot and delicious when the contents of any ceramic container would long be stone cold (a property I can't praise or stress too highly). And whatever the plastic may be, it's as odourless and discrete to the tastebuds as any bone china.
It was so good, in fact, that when my first one finally became a bit awkward to use after several years sterling service (wear, tear and general abuse to the softer plastic covering the handle) I attempted a dozen ceramic alternatives, looking for that indefinable "something", before realising just what a gem I'd lost. Fortunately, after a search on line (and after wondering whether Aladdin really now only made them in garish picnic blue), I found the self-same mug on line in a more discrete colour (and bought two to be on the safe side; one of them is sitting on my desk beside me as I type). I heartily recommend the product to anyone brave enough to throw propriety and convention to the winds and it a try.
Preparation? By preference, loose leaf, in a single-cup stainless-steel permanent infuser (one of the big, open-topped beaker-shaped ones I can spoon the tea directly into, with plenty of space for the water to get at the leaves - not a nasty, cramped ball).
Tea? Well - when the wife's making for both of us, it's PG Tips (because she finds it easier just going to chuck a couple of bags in a pot, whatever I may think about the matter, and I find it still makes a decent cuppa in the incredibly hard water around here). The merest dash of milk (if any), but again I find it tends to arrive by default (ah, well). If I'm making it myself, it's Oolong for its subtle, rounded flavour, or Gen Mai Cha (Japanese brown rice tea - aka "popcorn tea") when I fancy a more in-your-face treat. The basic Gen Mai Cha from "Char" in Winchester is excellent. (Not to be confused with their Gen Mai Cha Supreme, which some people clearly like, but I'm not so keen on. Oh, and their Earl Grey Supreme is pretty good, too.)
(Lapsang Souchong?!? No thanks. A drink for people who only have one working taste bud left. If I wanted a mouth full of the taste of wood smoke, I'd go swig Barbecue Sauce.)