Nauty is I think the best trade-off. The improvements in Saucy and Bliss (which have mostly been added to Nauty now) are useful.

The basic algorithm isn't that hard -- I have a few implementations lying around (nothing in Julia). Traces is better, but is much harder to implement and it isn't clear the improvement is worth it for someone implementing from scratch.

There are some improvements, particularly for graph isomorphism (as opposed to automorphism), but the basic algorithm framework is the same.