dx.com flashlights come from lots of different makers, some are obviously better than others, the cheap ones are clearly going to be more variable than the more expensive ones. I have one that flickers no matter how much I faff around with the switch, I also have this one:
http://www.dx.com/p/aurora-ak-p7-5-ssc-p7-c-8-mode-memory-900-lumen-led-flashlight-with-assault-crown-1-18650-17599#.V_wNaet4WK0
that I’ve had for quite a few years that’s been perfectly reliable, but it’s £38 so you’d expect it to be better made.
However, the torch I’ve used more than any other is this one:
http://www.dx.com/p/trustfire-r5-a3-cree-xp-e-r5-3-mode-230-lumen-memory-led-flashlight-1-aa-1-14500-39062?utm_source=dx&utm_medium=edm&utm_campaign=20120912#.V_wNtut4WK1
It’s as bright as anybody really needs a torch to be for general use, it’s really cheap, I’ve got six of them, three going back five or six years at least, only one has died, for no obvious reason, all the others work just fine.
I used to use them on my bike and helmet using Twofish Lockblocks, and at 230 lumens, capable of lighting a country lane quite adequately.
They use 14500 Li-ion rechargeables, or ordinary AA’s, the 14500’s are better, at 3.7v they drive the emitter harder, but they’re more expensive and need to be ordered online.
Swings, etc
Long-time use without issues means I can recommend both, the little TrustFire is the one I’ve used most, continue to use, and will for as long as they keep working and I can get (ever cheaper) replacements if they should finally give up the ghost.