sympy is good enough for typical uses. the user interface is worse but that doesn't matter to Claude. I imagine if you have some really weird symbolic or numeric integrals, Mathematica may have some highly sophisticated algorithms where it would have an edge.

however, even this advantage is eaten away somewhat because the models themselves are decent at solving hard integrals.

It's symbolics capabilities are still really good, though in my totally subjective opinion not as good as Maxima's.