If I should talk about heroes that can be good standalone units in many different teams then I would say Camus and Kagero. Xander is an honorable mention but I feel that he shines mostly thanks to cavalry buffs.
Camus - he's a great frontliner even outside of cavalry teams, mainly thanks to his good defense and speed. Vantage makes him into a big problem, that can't be dealt with sometimes. Also he's fun to play, because he moves fast and hits hard, which enables many different approaches to team building and in-game tactics.
Kagero - the ultimate antimage, and with +spd she can run desperation with confidence. She's also fun to play thanks to huge bursts of dmg to infantry units and she has a pair of insane anime boobs.
About Nowi - she's good, that IV is not worth 20k and I find her boring so I will probably never upgrade my ones. Can't say much about her for that reason.
Xander / Camus are really strong options if you are planning on running a horse emblem team. If you are not I'd say Camus is a stronger options (speedier + more offensive set. He requires more investment though as his native skills are weaker - grani's shield + cavalry C spot).
Both on +5 have a cool distant def weapon and strong stats. Depending if you need more of a red or blue unit, you'll decide.
Anna is definitely a good unit but very, very, very frail. One of her good builds uses fury + noatun + escape route + vengeance, which is funny to use but extremely squishy. I'm not sure I'd re-5* her if had the option again.
I wouldn't go with that Nowi. I'm not sure those IVs are optimal.
Mae is a strong blue mage. Your IVs are very good, she is speedy and can make very decent damage. It's a shame that TT are almost over, you could have used her to rampage them + get the bonus points.
Don't know about Fae, I'm not used to that character.
Those IVs are good for Kagero. She might lack some attack power, but being able to double will ensure many, many ORKOs :)
Good luck with your upgrade party !