I admit to being a Machado fanboy in MLBTS.
That said, I think Arenado is Machado with more power - or at least a less split bat (in OSFM anyway, Machado is lower vsL while Arenado is strong both ways).
So I think I'd take Arenado...but if I have to choose between them...talk about having a high-quality problem!
So...both. Move Machado to SS. Problem solved
Okay, maybe not...unless you actually have both.