Of the two I think BBE is going to be more annoying to deal with. Jace will probably help create either a caw blade reboot or a more solid w/u control deck, but people have to remember you can try and cram him into anything with blue but you wont succeed unless you can slow down the meta. That and he's now more vulnerable than when he was initially released since in black alone there are at min 3 cards that outright destroy planeswalkers,
dreadbore being the easiest to squeeze in if he becomes a problem.
BBE has always been damn efficient for basically being cast two spells either get another body or removal in the right decks and that translates into a lot of hard to stop value. The haste is a nice cherry on top. ALOT of things are 3cc or lower in modern decks.