The other lights have a sealed, non-removable battery and built-in charging. The P15 is designed to use a standard-size (18650) rechargeable battery, but neither it nor a charger are included.
The P15 is an older model, hence the low price. The 18650 battery is physically much larger, and holds much more energy than the built-in batteries of the other lights. Expect another £15-25 for a battery and charger, depending on where you get them. Note that batteries sold on Amazon and Ebay may be fraudulent and dangerous.
Whilst I'd prefer non-sealed, if it's realistically closer to £50 or so with a battery and charger to gain that, I will have to drop back to the others if I want to pay around £30.
In that case, do you recommend any of the others?
I can't find it for sale from a UK retailer (I'd want the proper UK warranty).
The Nitecore P15 looks to be in an entirely different class of lights from all others listed in the original post.
The P15 is an 18650 size utility light. It’s fairly large… too big for EDC, and not the latest model so the price is relatively low. It has a comparatively large reflector and a lot of mass so gives more throw and can probably sustain it longer.
All the other lights are keychain size with sealed internal batteries. It’s not surprising they have less output and less throw. They’re meant for an entirely different purpose… keychain EDC.
It’s not a fair comparison at all. If you’re going to compare lights to see which is the best value, at least compare to lights in the same class (1x18650 with recharging).