Choosing hyperconjugation when resonance doesn't give a reason for stability
My teacher says that while comparing the stability of the species concerned, we should remember that stability provided by Resonance&gt;hyper conjugation&gt;inductive effect. Of course there are exceptions(like in the case of chloro benzene where according to resonance the ring should be activated but inductive effect dominates it and the ring gets deactivated) to these but I think we can follow it in majority of these cases and there is no reason to not be confident about it.So likewise in your case resonance is not enough so you look upon the next one i.e hyper conjugation