The best duel is Yoda v Sidious . Flying Senate Pods! , need I say more? Also I love Sidious' evil laughter 
Im not a big fan of Darth Maul.
After watching ep3 Id put Vader v Obi Wan(Ep4) a close 2nd but for other reasons.
"Government is the great fiction, through which everybody endeavours to live at the expense of everybody else."
Frédéric Bastiat