BeOS/Haiku are surprisingly modern considering their age. They made a lot of technology choices at the time that short term were limiting (multi threading everywhere) but long term were very nice. It was just that the short term issues was one of many anchors of them when they needed everything to go their way.

Haiku is the closest of these to being daily runner ready but like a lot of systems, lack of driver support prevents it from that lofty goal. It is pretty much the only reason that Linux has been able to go so far.