Build quality is relative - but rear flimsiness is mentioned in reviews (i think - can't remember) - but it's the quality you would expect for a £60 case with 4 included RGB fans - it's swings-and-roundabouts to a degree. Once it's built, and unless you fiddle a lot, the slight flimsiness will be be forgotten. The fans will cool - but as to the relative silence that will depend on your curve and ear.Many people say the fans are not great and the build quality is bad? Really dont know just did a quick search
Unless you up your budget, perhaps ignore RGBs and adjust your fan limit to 3 (they will suffice) - you would be looking at something similar to this (i personally think it looks sleek/classy for a moderately priced mesh case):
My basket at Overclockers UK:
Review - https://www.tomshardware.com/uk/reviews/lian-li-lancool-ii-mesh-performance-review