Not only do you have emblems for Mits, but she’s a great utility hero with mana cut, equal damage to 3 and that blue reflect saves games a whole lot. You already have burn so JF isn’t needed much, and Ares is good but I think Mits will be more useful overall.
As far as titan team hmmm…Wilbur is a must and Marjana for sure, I’m not sure who else would be good out of those option. I’m sure others will give great feedback on that
I would also lean toward Mitsuko because she will also have utility beyond titan. 2nd place would go towards Ares solely from a reputation, I have no experience playing with him but I remember people used to love him.
I would make your titan team:
Wilbur - Boldtusk - GM - Marjana - Ranvir (a necessary evil).
Answering the direction question of the OP, ares would be a great choice for titans… BUT you have the attack boost in BT which covers all instead of only 3. If you’re not fighting 12*+ titans, BT can probably handle the job for now.
Marjana is sturdy but her attack stats suck… I’d go Mits and put her in over marj. (Mits’ attack isn’t stellar either, but at least it’s a special that won’t overwrite like all the other burns)