A lot depends on how I'm going and what I need to carry.
If I'm camping with a car, or with a group of friends, then a 2pt kelly kettle is great as it provides constant cups of tea, and can be easy to set going, especially at places where fires can't really be had. the cooking attachments are useful here, but I generally just treat the base as a small stove and put whatever I'm cooking in on it (billy can etc).
However, if its just me out, on foot, then the extra weight and size of the kelly kettle and the lack of need for that much hot water, means that I tend to just use a billy can over a fire or stove. Saying that, I can get away with only a cup or 2 of tea a day, I know quite a lot of folk for whom 2 pints of hot water is a 1-man serving