I had 2 x TraceRs – one on the commuter and another that swaps between MTBs. Under-saddle mount for both. Reliable, bright and decent battery life. Stupid little button aside I like them and would normally recommend without question, but after years of use I’ve now lost 2 lights in the past couple of years. Just popped out of their mounts. Probably partially dislodged unnoticed while moving bike around, frustrating regardless given the cost.
I’ve ordered a Moon Nebula as a replacement for the latest loss. Hopefully more robust mount that prevents accidental dislodging.