I've had good experiences with Behringer mics generally, and with their Xenyx mixers (not mixer amps - I prefer powered PA speakers), but I'm well aware that you're quite right about the inconsistencies.
I also have a Behringer guitar EQ that is the cheapest, nastiest little yellow plastic box one could hope to encounter. It has disgustingly cheap-feeling sliders, dodgy jack sockets... and it is great! It's quiet, it works brilliantly and, paradoxically, seems indestructible. It's been drenched in rain, dropped, kicked and generally abused, but it's outlasted my Boss GE-7!
My two favourite mics are both budget ones: this Behringer C-3, and a Shure PG81 that I've used on-stage to mic my mandolin.
Had an SM-57 and never really got on with it.