If I was going to mine with a CPU I would go with Monero. Seems to be the best out of the cryptonote bunch (definitely stay away from bytecoin - see the bytecoin scam thread for reasons why).
I think Monero has the best chance for widespread adoption out of all the cryptonote coins.
That's probably true, but sometimes it seems to be more profitable to mine other cryptonote coins and exchange to Monero, due to Monero's high mining difficulty.