Given its use in the other grappling arts, BJJ invented the guard.
The sixty thousand dollar question is who do you thing will have stronger skills on the ground ?
Answer:BJJ guys, because do ground fighting more often, not because they invented something new makes sense yes ?
Judo does not allow submissions beyond chokes and armlocks and has counter-productive rules like being able to stand out of a triangle choke. Therefore Judo is not complete.
My point is if you want decent groundfighting skills and a complete grappling package, a quality Judo club can give you that. BJJ is an awsome art which has carved a name for itself but don't write off Judo yet.