Rule 110: Notice the triangular "gliders" moving right. These are independent structures that can collide. This is what makes it Turing complete.
Rule 30: Looks random - used for random number generation. No persistent structure.
Rule 90: Perfect Sierpinski triangle. Beautiful but no interaction - just self-similarity.
Rule 145: Try "single cell" vs "random" - single cell looks complex, random reveals it's just a shift rule!