Arena mods- proper sets versus better speed secondaries.

It honestly depends on which toon you're trying to mod. For example, CLS, I mod for speed first, potency second, and then whatever else I can get after that. I'd make sure he has a matching speed set, but his other two mods don't need to match if they can't. Auto taunting tanks, on the other hand, don't need speed as much, so I'd make sure they had the appropriate matching sets/desired primaries.