Ethereum is always a good choice of altcoin if you are looking for good altcoins to buy. It is easily the best altcoin project out there and once they implement POS which removes the need for miners then the price of ethereum will go up higher than we ever imagined. There are some other good altcoins out there for you to buy too but ethereum is the best one.
I am in favor in Ethereum as it is the strongest Altcoin in the crypto market today.
But not only ethereum has the potential to surpass Bitcoin's, just like NEO, Bitcoin Cash, LiteCoin and ZCash... recently they're about to blow and their market cap were surging and investors earned higher profits and rewards of holding.
For me, top altcoins are worth to buy.