Probably a 3U 84HP would be enough, something from the likes of Pittsburgh Modular, although not sure of the depth of those cases. It's really limited when you get into something for portability and durability, they often come with a hefty price tag too.
They are all different, due to their differing circuits and components. However it's very subjective to what makes them pleasing to someone. What makes them differ is their individual features, eg. FM (linear, Exp), PWM, Sync (various types), wavefolding, Sub OSC, number of different waveforms, etc. Then you have digital oscillators, they can sound like anything.
Sounds like you are jinxed as I've never had this problem. I would have thought quality control is paramount for manufacturers, especially the smaller ones. The only modules I've had build issues with are the ones I've built myself, but that's just my cack-handed soldering.
