For the strongest wall, I would do the block wall set in forms poured in a deep trench (permit required). There are thinner blocks available which are easier to work with. Since “cinder blocks” are ugly, you can brown the wall and color-coat the visible parts of it after you build it. If you have the $$, you can use 99-cent std bricks or the more expensive bullnose brick (if the wall is not too long) crossways on the top of the wall for an extra (classy) touch :=]
