U-lock or chain lock?

Reviewers frame it as a versatility-versus-weight choice. r/ebikes and r/bicycling threads note chains like the Kryptonite Evolution 1090 wrap around awkward objects a U-lock can't reach, but they are heavy and awkward to carry. U-locks generally offer a better weight-to-security ratio, while chains win on flexibility around posts, fences and multiple bikes.