For boiling water ilfast it's hard to beat the jetboil system but you can get other cheaper systems that work almost as well and I find a bit more versatile for cooking and a whole lot lighter.

But my favorite is my trangia stove, it's not the most efficient, quickest or lightest. But I think it's the most versatile, you can fry some Bacon, make two different soups and boil water without having to wash in between. Also it's cool factor is 11/10