Should I level up light side character team or dark side?

So far my top characters are all light side so I have them at top level. Since I have not farmed many dark side toons except for sidious in the beginning most of my dark side toons are like lvl 50 while my light sides are 7* at lvl 74.
Should I spend the millions to lvl up the dark side toons even if most are between 2-4*? Thinking so I can complete the dark side missions. I have Vader as well