If you like a full frontal battle with little or no strategy, then Fenrir
If you enjoy a long marathon battle with little or no expectation then Rafa
Both Alasie and Ariel are great choice. Ariel if you need blue healer (for mono), and Alasie if you don’t want additional healer since you already have vivica, telly, rata, and albie.
You already have some serious damage dealers in your blue team. So I would go for Ariel, too. She is a great upgrade to Kiril who should be fully emblemed to stand his ground against the big guys.