Who to +10?

I have spent a bit in the game and made a +6 Like +10 Soren +8 Nowi +9 Effie for arena core. I have ammased 160k feathers and a lot of 4* units im considering maxing and bestowing distant counter.

1 Marth, love his utility but he needs atk buffs to take out hectors, good all rounder

2 Soleil, great combat stats to solo all greens but no utility, no legend weapon and i hate her art...

3 Eirika i love her but she just doesnt quite get there, her utility is medium and she needs set up to take down all the beefy greens.

4 Athena, i love her! And she can be about as good as Soliel but is just power crept, waiting for her to get a refine...

5 Raven. His upgrade isnt great w DC and as much as he can ohko people he strugles with mobility for that.

6 Pricila. I have @pa +1 and 7 shes more inique then the other choices but still niche..

Other options. Tharja. Corrin f. Sheena. Wait to see Roy refine (have 7 but hes so good fodder)