Probably the closest equivalent of Rio now is iRiver, in that they cram in as many neat features as they can think of, sometimes at the expense of usability. I don't think they ever made a player as good as the Karma, but netiher did they make a player that unreliable.
If you want a player that simply does what it claims to do (very, very well) then there is nothing to beat an iPod. The Video edition is gorgeous, and available in black
Although I've bought several iPods as presents recently, I can't bring myself to use one while my Karma is still ticking (umm, or in fact, not ticking, 'cos that would be bad).
Rob