A bit of both. Smoker was indeed stalling for Law and still put up an even fight, though I doubt he was holding back at all, as there would be no reason for him to wait for Law to finish Vergo off if he were capable of doing so. Vergo didn't use his full body Busoshoku Haki against him though, which would suggest he's overall stronger. From what feats were shown, it seemed as though Vergo > Law (no heart) ~ Smoker, though there'd only be a minimal difference between each of them.