For me, it's the opposite, but just because I can relieve my "pushing" muscles a bit by concentrating on pulling for a few strokes. In other words, I can last longer using foot retention (preferably clipless pedals and good shoes) than plain platforms.

I also think that clipless is a better option than toeclips. To get similar retention with toeclips, you'll need to cinch down the straps, which won't be able to release as quickly (and not without reaching down with one hand, either).

What to buy? That depends on which shoes you want to wear, IMO.