This is presumably so you can see where you're going rather than just be seen; what sort of terrain?
And I guess you've searched for 'running head torch' on Amazon and seen there's loads of choice, and are looking for recommendations from actual users.
I do have a head torch for lighting up the pavements and country lanes outside the coverage of Chippenham's street lights, or rather I have 2 - they came in a 2 pack, for just under £15. It's no longer on Amazon, although others by Apunol are. It's supposedly 400 lumens so definitely not the brightest, but why pay more than you need? It's fine for me, I'm very happy with it, and anyway it looks like you can get ones at least twice as bright for about the same price now. Mine's rechargeable, which means less weight (75g) as well as not having to buy batteries.
If you were anywhere near me I'd lend you my spare so you could try it out