The best race to look at is not 10k, but half-marathon. If we look at Bekele in his prime, he was in 26:17 shape, but I do not think he could last all 42k.
The half-marathon is where the top athletes(of marathon) run under 59' which is the standard right now. It is hard to tell if Bekele and Mo could run under 59' just yet because they have not been pushed from the gun on even-pacing.
My pick is Bekele over Mo with Bekele having more of an upside. The reason has more to do with the type of engine Bekele has vs Mo. Remember that Bekele could beat his competitors in many ways and in XC/roads/track. His race in the Beijing 5k was something that Mo has not yet demonstrated. He simply outran the field before the bell.
A healthy Bekele will be stronger than a healthy Mo.