Ethereum is a good altcoin because is the most popular after bitcoin. I think is a perspective coin.
Uhmmmm, Considering most popular=high volume, Certainly ETH has been most popular only after BTC, But nothing is forever, as you probably know LTC took his place as the most popular for a long time ago and it is now top 4, We see how long remains ETH as the second most popular.
The Etheruem still has quite active developr team. It also has good community support. It might stay there for some time.