Prob 72" unless you are doing big commercial sites... that 84" is a monster. There is a guy ebay with a 72" bobcat harley rake for about 3k and 200 shipping. I have bought from him before and he is a straight up guy. No hydro angle though.
My buddy does more grading than i do and he took the hydro angle off of his harley, we just dont use it. I had to grade out 50 acres for the county a couple years ago and didnt use my angle. Maybe some guys on here haVe a different opinion?