Where's a good place to dump Cantina energy? Also, what chars have shards at higher levels?

Thanks Slushie! Those are rather underwhelming. :/ Mace is okay but hasn't impressed me much the times I have tried him. Are any others underrated in some way?
Consular is about to be relegated to the sidelines once I get Luminara. But it will still be good to have another way to level him.
I wish Cantina energy wasn't so expensive. :(