Step 2: Best-Lock
They click perfectly with Legos and make a perfect substitute. They are also significantly cheaper, but they don't have as much of a variety of specialized bricks as Lego. I had to use a knife to take a misplaced plate off my son's pirate ship last night, so they stick as well as Lego bricks.
They lack the support ribs that the Legos have. That shouldn't be a problem, unless you're going to make a piece of furniture out of them.