The right side of my spacebar, followed closely by N.
My homerow is also quite heavily worn out.
Actually, all the keys on the left of the keyboard are quite heavily worn out. I guess its because of all the shortcuts I use on them.
My WASD keycaps are already very shiny. Thought they would last a little longer, but sadly not. But i'm not going to complain, they are pretty cheap, and the feel of them is pretty good for the price.
Hoping to get a Topre board with PBT caps, in order to see how long they'll last me.