If you’re after a totally proven, slick-shifting, long-lasting triple chainset for under £100, nothing beats Deore. Shimano’s lowest ‘proper’ mountain bike chainset gets solid forged arms rather than Hollowtech forged limbs but it’s still a durable unit for general trail use.
There’s a bit more flex than more expensive cranks but not enough to undermine your efforts. Shifting is very good too, with a steel inner ring giving excellent longevity and it’s available in both nine- and 10-speed DynaSys versions.
The external bottom bracket is a lower grade than SLX, XT and so on, but it still spins smoothly for months, whatever the weather. There’s also a nine-speed double-and-bashguard version, but whatever format you choose, the silver version is the way to go for more robust looks.