Having bought two amps last year (first time in years) I was researching most aspects you mentioned, but the the two most important things that held equal importance to me were tone/sound and reliability...
I spent weeks reading through all the SS and micro/class D amp threads as SS for me means less maintenance/greater reliability, and got a feel for which amps fit my tone requirements to narrow it down, then tried to find as many problem threads as possible, to know what to avoid.
So the order of criteria for choosing was really:
Tone/reliability> build quality >power > price > features >size > weight
To be honest I almost got into trouble early in my research/hunting when visiting a local music store that had a sale on one amp that I could have impulse bought at a good price, then decided against it until I looked it up here on TB and sure enough, for that very amp were a bunch of threads discussing cut outs and magic smoke ??? so I am very happy I did the reading and checking, and took my time. Another brand I was also considering strongly also turned up a heap of issue threads... both had multiple threads on getting faults repaired too... These were two big names in bass amps...
Oh and I'll save you a little time by saying the only micro I couldn't find any failure, cut out issues or seemingly any issues AT ALL that fit my tonal needs were the tone hammers... Runner up, Genz amps.. So that's what I bought, one of each... Good luck !
Edit: just to add that the Hartke amps were on my short list, great stuff... but in the end I chose to go the micro/class D path as I've been lugging amps a long time
