I have Ranvir at +8 and I have Frida, Ariel completely ascended. All my fighter emblems are on Kingston +9 and I have 750 barbarian emblems, +20 on Little John and some on Grimm. Who do I ascend? On one hand I have a titan killer but extra emblems, on the other I have a good finisher but no emblems.
Mikki is only good for titans, but he is the BEST for titans. Seriously, he gives better average damage boost for tiles than Ranvir. The ONLY titan he’s not the best choice for is the Thunder Unicorn (reflects blue damage).
The question you have to ask yourself is what is the most important part of the game for you? If it’s raids, then Fenrir is the only option. If it’s titans, Mikki is the only way to go.
In my honest opinion, you just need to ask yourself - do my Titan attacks need a boost? In which case it’s got to be Mikki.
Or
Do I need another strong hero for war and raids etc? In which case it’s got to be Fenrir
Good luck