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..