I'll be the first to toute Overeem's awesome K1 standup level skills and he's a massive fucking HW, however Cigano's crisp boxing, genuine and constant head & body movement and serious power will somewhat negate that and the height and reach aren't at a terribly disparity, so as you can tell, I'm leaning towards JDS. Overeem isn't the fastest draw in the west and I think Cigano has the handspeed which could be a defining key. I haven't had the privilege to see JDS's jits yet, but he's a brownbelt with Nog, so I think he can handle his own on the mat.
I see Overeem not being able to handle the flurry Cigano blisters towards him and after a few exchanges is unable to maintain a solid clinch and will be picked off and KTFO'd.
MY MMA RANKINGS
HW Cain JDS Werdum Cormier Barnett Bigfoot Overeem Mir Browne Nelson
LHW Jones Machida Evans Hendo Goose Teixeira Davis Shogun Mousasi Bader
MW ASilva Belfort Weidman Jacare Okami Rockhold Kennedy Consta Bisping Boetsch
WW GSP Hendricks Condit MacDonald Diaz Maia Fitch Kampmann Ellenberger Pyle
LW Bendo Alvarez Grant Melendez Thomson J.Miller Diaz Pettis Chandler dos Anjos Gray
FW Aldo Mendes Curran Lamas Frankie Zombie Cub Lentz Kawajiri Siver