I do a bit of both, depending on the day or on the same commute.

Some commutes I push hard to try to make good time overall. Others I slow down and just enjoy the ride.

I track my commutes on Strava - so sometimes even if I take it easy I may push myself on one short climb to see how I do.

I think a key factor though is if I am pushing it because I want to push it or becuase I have to be in at a particular time for meeting. That later causes stress and I enjoy it less. If I have the luxury of time I enjoy pushing it often knowing that I am only pushing it because I want to, not have to.