Of coins that have any buyers, Ducats is probably the easiest to mine, but don't hold your breath thinking it will make you rich. All these coins, including Ducats, have very low volume and weak blockchains.
This is the best thread on CPU coins:
https://bitcointalk.org/index.php?topic=379601.0;allReviving and updating the software of an ancient altcoin, like Liquidcoin or Tenebrix, whilst CPU mining it to build a sizable stash and then promoting it, would likely make one more money than mining toy coins.
Few noobs were around during the great BBQCoin revival. BQC had been a zombie coin for a very long time, with very low difficulty that made it easy to CPU mine. I and a few others quietly mined it month after month, fattening out wallets with little more than 1 CPU core. Then it was revived and some of us made fortunes overnight.