I've picked up a few torches over the years including the Tesco £10 2AA CREE. While that's ok for the price I've a smaller ThruNite Saber 1A that produces more light from a single AA battery and it has a better build with a good range of settings, very low, low and very high. While I quite like a simple torch (why oh why do so many come with a strobe?), a low and a high setting are useful.
My favourite torch is a Fenix LD25, is has a good range of settings and a way of swtiching easily between just two, it runs from 2 easily obtainable AAs and has a nice rubber coating so it's not too cold to hold in winter. Unfortuaneately it's discontinued I think. I've had it for a few years now, dropped it a few times and it still works.
Size wise, I prefer a 2AA torch for normal hand held use but if I'm likely to need to work on something a single AA torch is easier to hold in the mouth for a few moments.