Both are fine. Porcelain is stronger, but this isn't a big issue since either one will last longer than anything else in your home if it's properly laid.

That said, most of the tile I'm really drawn to is porcelain...

And if you are doing a pattern that will require a lot of custom cutting, a solid body porcelain is way the best since the color goes all the way through instead of just being on the very top.

The first day I had my ceramic tile down I dropped a pan lid and it bounced . . . six chips. Now I use porcelin as the color goes deeper.

Porcelain for kitchens

Porcelain is also my kitchen choice. But when you said "properly laid", can I lay the porcelain on top of my old vinyl floor which is on top the plywood subfloor? That's suggested by my GC. Does it sound right?

I would highly discourage that... although it is done on occasion, there is nothing at all proper with that method. I could not give you an accurate figure on how many times I've torn those jobs out.