It's hard to compare utility to being slightly better in combat, but i would say swordmaster simply because you already have rennac by the time you're expected to promote
In a normal FE game i would say Innes, but if you take into account the tower of Valni then yeah Neimi is much better. You're able to give her a mount and 1 range, which is great, but if you're not using the tower than she's gonna be a pain to raise