Not sure if frozen custard applies, but I find it typically better than traditional soft serve via McDonald's, Dairy Queen, etc. I've found Milwaukee Frozen Custard to be consistently quite excellent.
In the northeast USA, my choice is still Carvel for soft-serve, even if it's not quite as good as it was 30-40 years ago. It was creamier back then...but it still tastes quite good today even with the changed formulation. Tom Carvel is probably turning in his grave, though.