really, it's 6 of one, half dozen of the other.
that said, at the moment of having literally just gone through this, i would say do the floor first and have lots of good coverage/tarps on it once done to do your framing, sheetrock, painting, etc.
that's because the *&%^!! concrete grinding makes a ridiculous mess of everything that will take hours & hours to clean up on the nice walls, paint, lighting, etc.
(and yes, i could have spent a few hours taping plastic over all the walls, ceiling, lighting, etc., but I got lazy. will be making up for that big time....)
p.s. regarding protecting the bottom edge of sheetrock if hosing out the floor (assuming doing walls and everything else first and floor last), i used 1x4x8 pressure treated wood leaning against the bottom edge to protect it while hosing/power washing. worked just fine.