Another vote for the hub dynamo. I discovered somewhat to my surprise that there was a certain amount of hidden stress involved in using battery lights, which I didn't realize was even there until it was no longer there. It's nice to not have to think about whether I have my lights, whether the batteries are charged, whether I should bring extra batteries, etc. You just get on the bike and go, as fietsbob said.
FWIW, I have the Lumotec IQ Cyo R Senso Plus (I think; I'm not actually sure about the "R" or the "Plus").
But it has a standlight, which is very important; it's bright, which is very important, and it has a sensor (that's the faux-Latin "senso" part of the name), which turns out the light automatically when it's dark - although not as important as a standlight, I like this feature quite a lot because I don't have to think to turn my light on, and it comes on automatically when I go under a tunnel.