Checklist on the ground, memory in the air for me.
I had a checkride with a certain large UK PPL school's instructor once who chastised me for not reading the checklist downwind. He wouldn't accept the fact that I covered all the relevant items from memory (via the mnemonic BUMPFFLS), in a much more safe manner than reading the checklist.
IMHO a busy circuit is a dangerous place to be heads down on the checklist.
foggy.