Without a doubt, it has to be tea... English breakfast tea or Irish tea. The key most important characteristic I'm looking for is heartiness. I tend to buy Twinings brand. Of the standard, mass-market brands, I favor Red Rose. A bit of honey and a spot of milk or cream.
As an American, this hasn't always been easy. Tea drinkers tend to be second-class citizens in the colonies. The only time, this side of the Atlantic, that I didn't feel this way was when I was visting friends in Nova Scotia. There, at a tiny fisherman's co-op restaurant near a harbor, was a dedicated Bunsen machine with freshly brewed tea - a special, particularly hearty blend favored by fishermen in Atlantic Canada. Alas, it is no longer available.
I used to be a big Scotch and Irish whiskey man, but I don't drink alcoholic beverages anywhere near like I used to - no problem there, just personal preference as I get older. But I do enjoy the occasional Guinness or Harp.