Those are nice bins that were poured with poured walls. I go for the big blocks on 6" pad. I'm with Picasso on being afraid to knock the poured one over. However that is a cleaner look. My bins are between 6 and 8 feet tall. As I noted in the other post, the rebar and wire doesn't hold up too well along an 8' tall wall of blocks on the back edge of a 6" pad. We are experimenting now with a 18" to 2" deep footing under the pad, the width of the wall along the run. Hopefully that will work. It took about 8 years for the first set of pours to crack enough to need maintenance.