Which one is the best cryptocurrency next to bitcoin?
I would say that ethereum would be the choice of most of the people as its price is low as well as its price increasing percentage is high.
Some of the new investors would even say as ripple but they fail to note that only its marketcap has increased high due to banks using it for transactions and actually its price has not increased that much.
Agree totally with XRP but I expect it to 2 x in the next few months once it recovers. Personally, I like Powr, I just like the concept and this coin has a lot of growth potential.
In answer to OP, ETH in my opinion is the 2nd biggest and seems to have less limitations compared to BTC.