Unfortunately I can't give an opinion on the brands of shed, as I'm building my own...but don't let the others give you a hard time about the size. Mine is only going to be about 5.5x6.5, all the room I have to build one and sometimes it's better to have a smaller amount of stuff organized than a huge room full of ****, ya know.
Mine will be big enough for a mower, string trimmer, wheel barrow, shovels/rakes, fertilizer etc....what more do you need
Plus my lot is only 1700 sq/ft or so, so I don't have much room left after building my garage...if I want to keep a yard and deck.