For a silicone spatula, you need very flexible rubber. Nothing hard, no no. we have lots of spatulas with hard rubber, and they stay in drawer.
For a all around spatula (the kind for flipping things in a pan) you need sturdy metal. It depends, sometimes I need a thin one, sometimes it doesn't matter.
For a non-stick spatula, you need it to be metal, coted in plastic, or silicone, or whatever they use. I had an all plastic one, and it broke, it's almost completely flat now.
For a all around spatula (the kind for flipping things in a pan) you need sturdy metal. It depends, sometimes I need a thin one, sometimes it doesn't matter.
For a non-stick spatula, you need it to be metal, coted in plastic, or silicone, or whatever they use. I had an all plastic one, and it broke, it's almost completely flat now.