Personally (if it were me):
I wouldn’t do telluria as you don’t really need a strong strong green tank… If your alliance rolls thru tanks then there isn’t a need for a super green tank… not when you already have a great raid tank in Ursena.
Tarlak isn’t needed really… unless you’re annoyed enough with his missing on titans causing you to miss stuns… Mathematically Ranvir & Wu Kong are both better than Tarlak for damage boosting BUT Tarlak offers the heal & no miss. Read more here: Titan Damage Boosters: Miki vs. Tarlak vs. Ranvir vs. Wu Kong vs. Guardian Gazelle
I have no real experience with Chameleon so can’t comment much on him
Margaret is great but I still feel she’s mainly pitched at being a Titan specialist… The Damage made her more usable on Raid Offence but I still feel her primary roll is as a titan damage dealer.
Atomos will link in nicely with your existing Atlantis defence team… He also offers great use on offence (big damage) and titans (nice high attack stat) so I would say he’s the most well-rounded (now) of your options.