Skimmed milk for me. At work semi skimmed. That's what works for me.
For me, full fat. It tastes of milk. Real milk. (Otherwise, I prefer it black, none of that insipid, tasteless stuff, that lacks both body, and taste).
Actually, my real preference is for the sort of (organic) unpasteurised milk that I used to have as a kid, the kind that came in bottles, from a local dairy, delivered to the door by a milk man, bottles where we would fight over the rich cream that floated to the top - who got there first would pour it on their cereal - and, when drunk from a glass, it would coat your lip like a white moustache.
My cheesemonger now stocks some, the kind that comes with cream at the top of the bottle, amazingly delicious milk. The only drawback is that as it is not pasteurised, and has none of those idiotic additives, - but, being summer - it does have a short shelf life. Once opened, it needs to be consumed within 24 hours.
And, if there is no full fat milk, (preferably, organic, unpasteurised, creamy), well rich, luscious, double cream for me. Preferably, from Jersey, or Guernsey (I will pass with averted eyes over their unfortunate specialism in weird financial instruments of a morally murky nature).....