No altcoin is currently scalable. Ethereum is probably the only project that has all the incredients to make it work: funds, a huge capable development team, a roadmap, plans how to scale it ( securely ) and support and backing from corporations and institutions.
But with every new fork there is also possibility of splitting of ETH network just like how DAO disaster lead to ETH and ETC split. Main problem about ethereum is they have centralized ethereum foundation controlling all the developments. 
There is an article about alts with faster confirmation here https://themerkle.com/4-cryptocurrencies-with-much-faster-block-times-than-bitcoin/