Gawd. They're both horrible.
The old CapriSun pouches; I could never open those. I'd stab the stupid foil with the straw until the straw bent or broke.
The new CapriSun pouches - you stab them in the side so it's a little easier to open. Unless, you're me and stab then resulting in a huge tear spilling half your drink.
JuiceBox: These also suck. Either the stupid straw hole is covered with some impregnable material resulting in the straw deforming and breaking or you successfully stab it with the straw on the first shot resulting in a geyser of your delightful juice spraying all over you.
Or maybe this is just me...