Kdenlive also uses mlt, in the same way and is arguably easier to use in its newest 19.04 version. If by builtins you mean effects, kdenlive has so many of them

Kdenlive also uses mlt, in the same way and is arguably easier to use in its newest 19.04 version. If by builtins you mean effects, kdenlive has so many of them I doubt that OpenShot has more.