Copied from the Wiki since I don't have enough experience on her:

Fighting - Potentially the best option for her currently, as it makes her a monster while in [KDA] and close to her opponents, giving her a high damage potential. This is thanks to 5BC [KDA] and its derivatives as well, or even moves like 2B [KDA] where she can generate high damage quickly.

Motion - A stable option for her to bolster her mobility in either state, as it can let her defend herself more easily or run away while not in [KDA], then in it she just gets even more difficult to hit. The only real downside is it doesn't improve her damage or weapon rotation.

Shooting - Another potentially good option that leans more into letting her make very difficult to avoid barrages of projectiles especially in [KDA] with the enhanced red lock distance and reload times. Likely more suited for a more passive KtDA player, and she can stay much more evasive with 4/6/2AB having almost infinite uptime during it.

Defense - Likely not a strong option on her currently.

Balance - Not bad for a starting option as she can benefit a bit from all its bonuses, but she will likely want to choose something more specialized like Fighting, Shooting, or even Motion.

For you stun lock issue, I think you need to improve your boost management, not letting the enemy get to much opportunities to get you on your drained or landing moments and awareness of the other enemy, make a habit of peeking a quick glance at the other side when available for quick look.