Not sure what security you mean, for you return? From where?

If you are flying into LGA/EWR from YYZ or a few others (YUL and YVR possibly), you clear immigration in Canada. So there's no immigration or security on the NYC end. If terms of which has less traffic I imagine it depends on time of day. Flying out both EWR and LGA are pretty much a disaster. Also getting to them from I assume Manhattan (by midtown) 25-30 mins seems somewhat optimistic but again 3am Sunday vs 9am Monday is going to differ substantially.