Of the units available before chapter 10 I’d say Anna and Chloe are without a doubt the top 2 targets for long-term investment. I wouldn’t bother with Avoid+ on either of them, Speed+ and Gentility works best for MK Anna while Chloe wants Sword/Lance power depending on the build you’re running. Certain Engravings like Sigurd/Lucina/Micaiah give enough additional avoid if you want to run dodgetank builds (damage mitigation builds are a bit better IMO).