I've always thought of Blockland as a LEGOified Garry's Mod. Minecraft and Blockland aren't similiar. Except one aspect, and that is building, but Blockland is much better in that aspect. THINK about this: Blockland(basic, unmodded) has many, many different sized bricks. Minecraft(basic, unmodded) just has multicolored 4x cubes, slabs, and decent assortment of other interactive objects.
Simplicity is better for some people, and those people would probably prefer Minecraft, however, you could always just build with 4x cubes in Blockland. Hahaha