I've used just about everything in the RJ - the company-supplied DCs, my own ANR DCs, Telex 750s and Plantronics MS-50. Obviously the quietest are the ANR DCs, but they're tough to wear on legs over 1 hour (head clamps). Plus most Capts like to take off their headsets above FL180 anyway. The company DCs are next in terms of quiet, but more uncomfortable than my own. The Plantronics MS-50 with ear mold was ok - super lightweight but no noise filtering at all. My biggest complaint was that I only had sound in one ear, so I always had the overhead speaker on as well. Finally, I tried the Telex 750s. For me, they're the best choice - lightweight, a (very) small about of noise blocking, and sound in both ears.
At any rate, the CRJ is very quiet below 280KIAS (we're almost always below 280KIAS at altitude; .74-.77 mach). Above that, there's a lot of wind noise.
Anyone interested in a set of Plantronics MS-50? $45.00 - Can't beat the price!