In order to be able to compare you have to be sure they are scanning the same things and at the same level of inspection, this is very hard to do unless you know exactly what will be scanned by both AVs for the settings you use in both.

You also have to ensure that there is only one AV installed at the time you run any test as even if one is in theory disabled there could still be conflict which could effect your results.

Speed is only one aspect (but without knowing the depth of scan something that can’t easily be judged) and I would suggest not to important when compared to detections and functionality, after all you could start your scan and come back later, go to bed, etc.