These days most of the coins that launch are all ICOs or some type of ETH token. Very rarely is a new POW coin released these days. These aren't the days of 2014 where everyday there was some type of Scrypt algo coin released and you can instamine it and then dump it 24 hours later when it got listed on Poloniex (top exchange back in 2014)
So basically ETH is currently the most profitable especially for GPUs, there really isn't any secret coin out there. Times are much tougher now for miners than they were a few years back. Too much saturation in the markets unfortuntaely and not much profit left to be made.
i think that something must to hapen. theres a lot of new algorithyms and its not to algorithym but what bisnis idea stands behind the coin i agree that as you said eth is most profitable coin but to develop the market theres must be new bisnis ideas and new types of coins that suports them.
No because POW is actually starting to get phased out because many consider it to be a waste of electricity and many people pose it causes centralization if there are a small number of parties that control most of the hashrate.
Hence if a new project or coin wants to succeed, they usually avoid the POW road which is bad for miners. Hence why many project these days are ICOs or ERC20 tokens. And most that develop their own blockchain afterwards are usually POS type of coin.
Are these secure? Nobody really knows because they don't have much adoption these days except those people that buy the tokens to just speculate on them. However they aren't used in everyday transactions like most BTC and ETH transactions.
maybe when btc mining will be exausted there will be free place for something new becouse big procent of hash power now is used for mining btc