My experience is that it is the GPU fan that is often the noisiest, especially when it is a bit long in the tooth.
For that reason, I try to only use GPUs designed without fans, just with large heatsinks. All 5 PCs currently in the household are so equipped.
I agree that larger diameter fans at lower RPM are quieter, but one is often limited by the case when it comes to replacement.
Most fans do specify the dB level they operate at (whether you believe the figures or not is another matter), so can be used to guide purchase of fans.
Cost and quality are generally directly proportional, so cheap fans are rarely the quietest.
Unless you are doing serious over-clocking, cooling is highly unlikely to be a problem, and as MB says, investing in quieter fans is a much better (if not as satisfying for the tinkerer in you) solution than water-cooling.
SD