I used to own Nite Rider Mini, 110 lumens - not much, but it worked well, even during moderate-speed winter-night rides around Dartmoor. But it got nicked with my bike...
When getting a new bike I bought some Lezyne Mini Drive. Small light, 150 lumens. Unbelievably short battery life. Good as "be seen" option.
Then I got a Magicshine MJ868. £79.99. Maaaaan! My life has changed. I do a night ride every week, Dartmoor and Totnes are, I also commute with it everyday - this light is fantastic! Powerful, nicely made and the battery package seems very solid (it looks better then on higher Magicshine models actually). Highly reccomended.