I have top opening. It's a PITA 'cause you need one hand to hold it open while you deal with what's inside with just one. Of course, you could add some sort of latch to hold it open. I haven't figured that out yet. NOT a handy person, as you could guess...
I used a short chunk of 2"x2" to hold my top-opening box open while I collected eggs. But water inflitration is why I changed style.