I'd get a petrol one, but the extension lead will also be useful for plugging in stereos and grinders and the like - whereas getting a new hedgetrimmed would be pretty much a one trick pony. Until they legalise me chasing cats out of the garden with it...
Ideally, all coiled leads *should* be fully unwound when plugged in, which may (or may not?) make a 25m one also a 1 trick pony, only used for the hedge trimmer.
Strangely enough, for some bizarre reason, I had a lot of visits from the fire brigade to give advice, and amongst all the other advice were these 2 electrical ones:
Coil extension leads, always fully unwind when plugged in (I always did when actually in use, even if under the wound limit, but they say even when in use).
Never use those 3 way block type mains adapters, to plug more than 1 plug in a single outlet. Not recommended, but if you do need more sockets, use those standard 4 way ones on a short cord, from a reputable manufacturer.
One of the possible reasons for what happened here was a coiled extension lead plugged in when fully wound, even though nothing plugged in.