It's particularly tricky when it's online. You can do your best to record the bass accurately and transparently (impossible, but worth trying) but you don't know what kind of speakers people will be hearing it on. I can only differentiate a few basic tones through online demos; a gnarly aggressive one like a Warwick or Musicman, a warm mellow one like a P bass and.... maybe the sound of a short scale. Slapping sounds identical on all basses to me (and I kinda like slapping, god knows what it's like for people who don't).
Ed Friedland has been mentioned but, a bit like BC'er Scott Whitley, you get the impression he could make a bass out of cardboard and twine and make it sound good.
I'd say a decent demo would be scales that use most of the neck. A major scale that goes from root to 12 starting from the 1st fret on the E, then 5th, 9th, 12th and 15th would do it for me.