[Darvin]

Generally when I hear "strongest", I think "best".

In any case, bottom line is that I feel that races shouldn't be about "better" this or that, but rather "different" this or that. Each race would have different advantages and disadvantages for each unit type. If that were done, there wouldn't be a problem with mount combos, since which ever you chose, you'd have to deal with that mount's weaknesses.