Okay the three point I have high-lighted above are for the following reason --
- Corsair cabinets are overall good in build quality, Cooler Master 690 is an old design and has a long run in production. So I think good build quality is speculative.
- The Corsair Carbide apart from the bottom location, supports the Corsair H100 easily in the same sandwich configuration at the top. Also, I have seen plenty of Cooler Master 690's / 690 II and 690 Advanced in my time and removing the top cover is frankly an exercise in wrestling.
- Side Window is also a speculative addition it doesn't improve performance.
Okay the hard-drive cages on all Cooler Master 690's / earlier HAF models are like that and are flimsy, I prefer the simpler snap-on system used by Cooler Master STORM products and NZXT.
Those fans you mentioned are Cooler Master SickleFlow's they are available cheaper on the street, the price ranges from ~400/- -->550/-. I will not call them quiet but yes thy are a lot better than the stock fans you get on a cabinet, to reduce their noise you can under-volt them further.
Just my point of view, Cheers!!