The worst I've ever used, a cheap AA "flashlight" that sticks out like a **** from a single band on your forehead, clumsy to turn on and off, was still not bad and way better than not having anything hands free. Not comfortable to wear for long, not much light, still worked.
My best is still a cheapo $5 type from ebay, but its flat and a bit more comfortable and easy to use, has ok output with a COB. My other $5 has a couple modes including a red LED for not losing your night vision or bothering others, but output is a bit weaker and battery connection is flakey at times.
Upgrade plans would be a better quality, maybe with the battery at the back of my head instead of one piece types. The option of lower level red only output is very handy, but not a deal killer on a new one since I have my old one that does that part fine.
My advice, buy a good one if its work related, buy a cheap one and see what you do or don't like before jumping into a $50 light.