I think ethereum is one of the best choices on the current market. Also, I think some altcoins which have prices under $1 like cardano and stellar can give good profit in the next bull season on the markets.
Ethereum still an excellent choice to invest but it's too expensive for some people, and they have another option to invest in the cheap coin. Fortunately, we have too many good cheap coins to invest, and I agree that cardano and stellar can be a good choice also and we have the other coins for investment. And if you have $100-$500, you can buy a lot of cheap coins, and this is what I did too. I will purchase cardano, stellar, ripple, tron, kyber, xem, and the other cheap coin because I am sure that low coin price will have a big chance to increase higher.