Black star and tsubaki were really strong from the begining.
And even if black star is very annoying with the whole "i'm greater than god"crap, he is very serious about getting stronger.
That said, maka and soul are just the basic main characters who get stronger through struggle and getting up and down through their relationship. So they are really noting speacial, especially not when it comes to strength.

However either probably could win in a fight but I'm going with Tsubaki-chan and Black Star here.