I think this was done before, with the consensus that Cheetah wins. She's physically in the same general strength class, but way faster and'll slice him up with her claws.
Cheetah for the majority. Namor is likely stronger, contextually (while Barbara holds her own in fights against WW, that is largely due to her speed and the element of surprise; Cheetah is much stronger than many realize, but she's demonstrated repeatedly as not being as strong/durable as WW, and similar), but the speed/claws are going to be hard for Namor to fight against, barring CIS on Barbara's part (her occasional weakness for wanting to "play" with her food could leave a window of opportunity open for Namor to exploit).
__________________ Why am I here commenting on this crap?
Flight pretty much results in 'Get a bit too close, gets tail-grabbed to the ground from an unexpected leap, clawclawclawclaw at superspeed' against her, traditionally. Both Wonder Woman and Superman have fallen prey to this.