Back in 2014 you had maybe a dozen or so coins to mine. LTC was the most profitable but from time to time there was Dogecoin, Darkcoin (now DASH), Maxcoin, etc. And every week or so there was 3-4 new coins released that you could mine for a few days with low difficulty, then usually in a few days they almost always got listed on some exchange. And usually sell for a large profit when it hit the exchange.
These days thanks to ETH and their ERC20 tokens. Most projects go straight into an ICO. You need to pay for the tokens, you can't mine them. Hence ETH is the most profitable for GPUs and XMR for CPUs and if there is some other coin out there the profits will more or less be the same since there are bots which hop from pool to pool based on profitability. So these days just save yourself the hassle and just mine ETH.
Well said, why look for a new coin to mine when 99% of new projects today are going for smart contract? If POW algorithm is still a big thing like that of 2016 we will keep seeing new PoW coins almost every day, stick with Ethereum and make your ROI back faster