According to me Vader is quite good if used properly. And it is even better when used along the Tank or the Emperor.
The only possible change would be some force power to give him jump or some sort of force speed (velocity becomes 2 for one turn but you have to exhaust it).
Sincerely speaking also Jyn Erso is very powerful.
And when considering a commander or operative, you should consider also the command cards the bring along. Eg. Director KRennic has nothing strong in his stats: poor attack, less trhan average defense, a good amount of wounds, average courage value. But his real power are his command cards and two of his special rules: cunning and entourage. But it costs the same of Leia