I was leaning towards the Laney, havn't had any encounters/experiences with any Randall product, and the only person i know who used one was Dimebag so i'm not sure about the Randall.
Valve king has gotten a reputation for being cheap cr@p from a lot of people, and it probably is for the money spent on it. The Laney i think will be built nicer than the others and will have a lot more gain than the Valve King.
Though i cannot try the Laney before i buy which sucks.