Which survivors to invest in?

Burmeliinis

I have a varied lot of survivors picked up over the last few months. Which ones of these would you invest in? Elaine looks quite solid, so I feel tempted to see which the fifth trait would be.

Cronus

If Rose got Marksman or even Sure Shot she'd be worth advancing (Vigilant, Bullet Dodge or Def Stance and she's token fodder).
For Mel I'd probably have to pull Lucky or Iron Skin. I'm not super high on Ruthless or Revenge on Assault class so I'd probably look to Rose's 5th first.
For me Andy would likely becomes tokens. Def Stance on a Warrior is why (for me). Lucky-Dodge-Iron Skin-Ruthless are all good however without Retaliate I'm afraid he has a limit to his usefulness.
I like Elaine over Danielle but she needs to pull Lucky, Ruthless or Dodge as her 5th. Lucky, Dodge and Ruthless would be so much better than Revenge on her.
Eva has pretty solid traits overall. You can equip her with a High Powered weapon and use her in Overwatch (Vigilant) or stand in place and fire at an opponent (Sure Shot). Shooters in Overwatch with a High Powered weapon are useful.
Sarah due to Def Stance is probably in the long term going to be tokens for you. Tiffany has better overall traits and you still get Revenge. Ideally for a Shooter you'd look for Lucky-Dodge-Ruthless combo. I'd probably invest in your favorite Shooter per your style of play and look for Shooter with better combination of traits (esp with Ruthless).