I've played plenty of great sounding amps with 15" speakers, including Tweed and brown Tolex Fender Pro amps, and BF Vibroverbs.
Of the less vintage end of things, the 1 x 15 Peavey Delta blues is also is a great sounding amp, as it the old WEM Dominator.
15" speakers are generally favoured by rockabilly and pedal steel players for their extended bottom end, although of course Ritchie Blackmore did quite well with his 4 x 15 cabs!