Not sure about which one is higher quality but when I replaced ours, it originally had a 30 amp Lyghtpower. Searching on the internet I found a WFCO transfer switch with the exact same model number relay. So no difference in quality. Per many here on the forum "WFCO" isn't too appreciated, at least for their converters.
Since they were identical, I planned on swapping out the relay, but when I got it the WFCO case was a smaller foot print and a bit better design so I swapped the whole box. In March they were running in the average neighborhood of $60. I lucked up and found one that said "not in original packaging" for $27.
Per darsben1, you can just mount it on any surface and wire it up. If wired properly it should not get hot. But since I've had one melt the wiring, I prefer having it wired in some type of metal enclosure.