This may open a can of worms. But I think it depends on how durable the opponents are, and what arsenal they're working with. A fast opponent fighting a tank who is so durable, they can shake off their attacks is going to be bad news for them-because it's going to take more+bigger fire power to hurt them. Because in this case, the speedster is going to tired down faster possibly, due to having to run around their opponent-which will exert a good bit of energy, while simultaneously using alot of fire power to bring down the tank-which may be additional strain on their body.
So the tank may have a hard time touching them. But when they start to wear down, they'll be easier to catch. So speed needs to have some damn good, powerful and/or hax abilities to bring their opponent down before they get too tired.
But speed can win provided they're not fighting a huge tank, and have seriously effective attacks.