Just discovered one of my lights has died, but still got one going. Anyone got an opinion on whether I’d be better off having it on the bars or the helmet?

Depends what it is I guess.

What type of light was it, and can it be easily repaired? (snapped wire in connector, dodgy battery?)

Off-hand I’d say bars, as I’ve always found helmet light on their own tend to flatten the terrain (no shadows to see the bumps) – the best option is to have both obviously.
BUT until the undergrowth dies back a bit, you’ll struggle to see round corners, so the helmet light is more useful… s’not a black and white choice 😛

helmet for me

Deffo the helmet.

Helmet for sure. There’s advantages to bar mount too but more for helmet.

Unless it’s misty anyway!