kind of an odd thread, but ill put my two cents in
HW= Fedor vs Lesnar- too unpredictable, see any of the million threads about this.
LHW= Machida vs Mousasi- I would have to give this to Machida, but again, very unpredictable
MW= Shields vs Silva- Shields gets his shit pushed in
WW= Diaz/Zaromskis vs GSP- GSP beats either of them at this point IMO
LW= Penn vs Melendez- Penn wins anywhere he wants.
Thats just the champs, and honestly this is the only format Strikeforce could be competitive in, if you faced off the top five or ten fighters in each weightclass, Strikeforce wouldn't have the depth to compete.
UFC has the bigger roster and alot of the Strikeforce fighters are UFC castoffs. If Strikeforce continues to grow the way they are now, this could be way more competitive in a year or two.