Barring a direct hit in which case nukes would be very effective, why would nukes be particularly more effective than conventional explosives? Presumably space faring ships would have to be extremely heavily radiation shielded and in a vacuum explosive force is largely irrelavent.
Doesn't really matter how big the bang is in a vacuum.
Dont forget the heat a exploding nuke radiates. A often overlooked aspect in SciFi is that heat management is quite a problem for spaceships as they have no way to remove excess heat besides slowly radiating it.