My favorite ever are the Hunsaker Quikfils (http://www.quickfilljugs.com/8-gal-q...jugs-c-35.html
), but they are expensive. They are suspiciously cheap here: http://www.polyperformance.com
, so not sure how they got the price down that low.
My most recent purchase was for two of PU-Products "utility jugs" (http://www.sidebysidesports.com/5utjug9.html
). They are super easy to handle, but don't fill as fast as the Hunsaker. I liked them because they are tall and take up less floor space. However, that also means they fall over easier when standing up in the back of your truck, so you usually have to strap them up. I think they make a rack to hold four of them, which would solve that problem, but I can't seem to find it now.
I like the ones with a handle on the bottom because it makes pouring a lot easier!