Iron MK II says:
"ok if it was a level playing field with no holes in the ground for obi to jump out and kill maul, who would win just a straight duel no obstacles around to help either."
As far as jumping up from the low ground or a 'hole' as it's stated, Obi-wan has shown he can win either way. He chops Maul straight in half when he jumps up from the low ground to attack Maul (Ep.I), and he messes up Anakin pretty hardcore when Anakin jumps up from low ground to attack him (Ep. III). Obi-wan proved his skills on both sides of the same manuever, so I do not see it as a factor. I do like Darth Maul better, but I can't really give him the win here.