My favorite was the R44.
I used to take it all the time for my summer college job once. It was the first series of cars to have the ♫♪ Bing Bong ♪♫ as the doors were closing. And the sound conditioning was so tight you could clearly hear the motor spool up and resonate from nothing. A consistent sound. I loved it. The R46's were close, but no cigar as, you couldn't hear that resonate spool up. Although they did have the "whistle break" release.
A lot of them were rebuilt by Morrison Knudsen, (as I was working on Wall St in the late 90's - early 2000s), so they lost that initial breaking sound but the sound conditioning and motor spool was retained.
I remember those fondly as well. The 44s used to be an A Line phenomenon up until 2009 or so. They had the blue stripe removed and turned patina. Very loud air releases but inside was as quiet as a library. Now they are designated to the Staten Island Railway. The R46s still dominate on the N, Q, and A lines. A lot of the cars on the 46 trains actually have disconnected motors and on one N train I was on last week, there were at least 3 cars with no propulsion. Only the air and door/AC electrical lines were on and they were literally being deadheaded with the other 5 cars pushing/pulling them along...
