Shimano UN54 square taper bottom bracket review
Square taper cranks and bottom brackets (BBs) ruled until about a decade ago. They might be officially obsolete but they still live longer than anything else.
There are some superbly engineered square taper cranks still available online in the form of Middleburn RS7s, Shimano XT and Race Face Turbines.
As long as you fit it correctly and tightly, the UN54 bottom bracket is squeak-free and stiffer than you’d expect given the external BB hype.
The last unit we replaced had run almost daily for close to six years, so you can’t beat square taper BBs for lifespan.