I am excited to replace Grimm (or C Kiril) for def down on titans, and Athena is probably the best at that. No Miki, I’ve pulled for him both when he was HotM and featured in Atlantis but it wasn’t to be. Currently using Tarlak as my titan booster.
I consider both Athena and Skadi as “must ascend” heroes, it’s more about the order I get them there.
To me after what I’ve read, the pros for Skadi are that I can almost create another war hit team just with her and some support heroes that might not be used elsewhere and have a high rate of success, and still keep my other teams with the heavier hitters. Currently I’d say about 60% of my war offense are 4*s although most of those with plenty of emblems and my last couple of teams feel weak/more board reliant. Also, it will be lots of fun to have Skadi for undead horde.
Athena seems perfect against red titans, and great for any blue stack on offense. This probably makes her more versatile, while Skadi seems much less effective without minions. However, unless it’s a war equalizer (thanks for the reminder @Lexxtarc), Skadi will probably have a place on a war offense team every war.
With the feedback so far I think I’m convinced that Skadi will be worth working on first though, even if Athena would be much better on titans.