What's the most comfortable neck strap for Canon SLRs?

If nothing has changed since the 20D days, I'm guessing the included Canon strap with the 6D would get a little uncomfortable after a while especially with a heavy lens. Have any of you replaced it with an aftermarket strap? I remember buying something from Op/Tech many years back but wasn't sure if that's still the preferred pick these days. Any recommendations would be great!