Three Units I want to Use

I prefer Sothe he has good atk, descent spd and can debuff enemies.

I wouldn't suggest picking units just based on which ones you have good IVs on. All three of them are fine units and their IVs are indeed good, but generally speaking I think you can get more out of your resources if you go for units that are good even with neutral IVs. If you don't have the preferred IV you could wait or merge into a better IV later (ex: I promoted my first Reinhardt when he was a TT bonus unit, now I just wait for +atk)

I noticed in one of your earlier posts that you really like Maribelle. If you pick units based on that kind of liking and figure out how to make them shine (because this is still a game where any unit can be good, not necessarily top or meta-defining but good and meta-effective), you will probably enjoy the game more, and in a way that is resistant to shifts in meta such as those caused by new super-powerful units being introduced or the coming arena scoring change.