Light/Dark Shard farming

Kesiss

Sorry, possible a dumb question but what is a good investment for 12 stam farming at lv.42?

Im currently doing Chew, JC, and Daka. Anyone else I should focus on?

Heezyyyy

Luminara

Kesiss

How about Rey or is it not worth it?

Jabberwocky

Don't farm anyone in LS/DS that you can get somewhere else (like Lumi in GW shipments) unless you're in a very big hurry to * up quickly.

Farm Chewie and JC in Cantina battles (if you have it unlocked?), Daka in Cantina shipments if that's what you're going for.

Use energy to farm gear in PvE missions, except for toon shards that aren't available anywhere else (like Lobot and Rey for example) and only if you really need them.
It's usually a hard grind and the low drop rates mean you'll be at it for a while. Don't spread yourself too thin farming too many different toons in PvE since you get more benefit usually for gearing up than you do for * level.

My advice is pick one, maybe two. I'm doing 4 currently but dropping to 3 since Dooku is being added to Cantina battles after I unlock the next tier at level 69. After the first two PvE energy refills, I'm spending crystals on refills at 100 each to do it and it's only because I'm almost maxxed on all my gear for my main squad and several other toons. Plus, I'm above level 62 where tier III gear challenges unlock that drops a lot of purple gear you need 20x or 50x of each.
Cantina battles energy is 100 crystals for the first then jumps to 200 immediately so I usually only do one a day.
If I still needed lots of gear I'd be shooting myself in the foot going after so many shards at once.

I usually place top 5 in arena so I can maintain the crystal burn rate for 100 crystal energy refills with only the occasional crystal pack purchase. Once you climb to higher levels, the rate at which you advance slows so you get less and less bonus energy for leveling up.