For me, probably the F. It's a little quieter than the F2 and the F3. But, not when the F-36 drive is in use. :-) BTW: if you want to be reminded as to how an F3 with MD-4 sounds like, just use the camera app on an iPhone. The sound produced by the iPhone is a sample of an F3/MD-4 combo being fired.
Want to be heard with a camera that's not motorized? Try an FM2n, FM3a, FE2, or FA for 35mm, a Hasselblad V-series body for medium format, or a Speed Graphic's focal plane shutter. The Nikon bodies have a definite *CLACK* when fired.