If maxing Ranvir would dramatically help your titan performance, I’d go for him. If not then I’d go for Mica, Vivica, or Delilah (and at the moment, I’m leaning towards Vivica).
According to Anchor’s grading sheet, Mica’s one of the best out there. A+. He doesn’t hand that grade out often. Mica’s rated higher than Delilah or C. Vivica. I wasn’t seeing it when Mica first appeared, though, and I admit I’m still kinda skeptical. I suppose I could see it on offense, though. He can keep the Wilbur effect going on your team from the very start with Charge 1, and he can preserve your crew until he manages to pull off Charge 3 and make you nearly invincible. If you bring a healer along, you’re likely set for some powerful longevity. You gotta knock out the dispellers, though…
I just pulled my first Vivica for costume summons. The more I think about it, the more I like the idea of having her around. Maxing Costume Vivica gives you both a cleanser and a dispeller, a Defense Up hero and a Defense Down hero. You just flip her card to match your moment’s needs and you’re good to go. I could see this versatility being valuable. It’s like ascending 2 healers for the price of one.
–Also,– I don’t know what your titan squads look like, but C. Vivica’s Defense Down could make a good bonus when stacking light heroes.
Vivica will also serve you best when Very Fast events come. Now that this applies to both tourneys and wars, that would tip the scales for me and be the last factor I’d need for my decision.
I could see Delilah being a good pick if you have other summoners. I don’t have any other insights to add there, though.