I prefer the 5 quart jugs. But on occasion, I've ran across a real good deal in quarts. Although I'm not fond of having to deal with motor oil in quarts, I will buy them.
I do occasionally buy the 12 quart boxes when it is a better value than the 5 quart jugs. But I keep an empty 5 quart jug on hand, so I can fill the jug from the box, and use the jug to fill the engine. This extra step seems a little annoying, so I'm not a big fan of boxed oil. If the savings isn't significant enough, it's not worth the hassle.