There is no DEAD SET top 5 builders that i know of... now i can point out the top 5 in my opinion builders...  but those will vary from person to person... again it all goes back to doing your homework and asking questions.. 
TOP 5 in my books IF price wasnt a option.. 
Funco 
Suspensions unlimited 
Buckshot 
Tatum 
Revenge Racing ( old Dunebuggy.com Builder ) 
If money wasnt a option those would be my top 5 to choose from.. and i would probably ask Kevin that used to work for S/U to build me a bad a$$ 2 seater..