There’s a huge choice when it comes to torches. These include wee LED ones, big flat LED ones, super bright halogen ones. It includes torches shaped like batons, torches for your head, torches for your shoulder, torches for one side of your head, all sorts.
The must-have things to look for in torches though, are the obvious ones. Make sure it’s waterproof above all else. If you can’t leave it to soak overnight in your bath, then it’s going to fail at some point when you’re out and about. Prefer ones that have multiple o-rings so that if one goes, the other will catch it.
Lighter ones are better for the same wattage, but as most of the weight is in the batteries the differences between similar torches won’t be that large. LED torches tend to last longer: their bulbs fail less often, sometimes fail gracefully (one element at a time), and use less battery. Halogen or incandescent bulbs can fail in one flash, and when they’ve done this to me it always seems to be when you’ve first turned them on on the first night. Some of the more expensive models have little holders at the bottom of them with spare bulbs, which definitely helps.
Beware of florescent tubes. You can still get these, but if the ampage left in the batteries falls below a certain level they simply fail on you.
It’s hard to overstake how much of a pain a failed torch in the dark is. If there are two of you you’re left constantly pestering your tired mate for a go of their torch. Everything takes twice as long. It’s disorienting and totally rubbish.
If your torch fails and you need to walk off the mountain, then you’re in real trouble. That’s when you start to get deep in it.
So go for torches you can depend on, are robust and watertight, and fail gracefully. You probably don’t need to take spare batteries as this adds a lot of weight and are rarely used, but for the small cost of them I’d definitely recommend replacing batteries often, and always if you’re going out for more than one night.