I do not prefer an external safety. My current EDC gun is a Glock 19. When I worked as an LEO, my duty gun was a Sig 226 or Sig 220, both in uniform and plain clothes. No external safties, only a decocker.
That said, I cut my teeth on a Browning Hi-Power. If I'm going to have an external safety on a gun, I want it to be a 1911 style safety -up for safe/down for fire.
I have used/carried Walther PPK style safety guns before (PPK/S, Beretta 92, and some S&Ws models 39, 3906, 669, 6906) I used these safeties as a decocker lever only, carrying with the decocker in the up - fire - position.
But I really prefer no external safties - even though I am putting a Springfield EMP through its paces right now.