My favorite would also be my only safe queen, a 1961 Royal Blue 6" Colt Python. She's beyond beautiful. To quell the urge to shoot her, I have a 4" Royal Blue Python of 1974 vintage, and that easily sits in the number 2 slot.
My .44mag Anaconda, .22lr S&W 17-4 , and 9mm S&W 39-2 would round out the top 5, and in no particular order. All classics, all beautiful, and most importantly, all mine, lol.