Ethereum is beside BTC my favourite coin till so far. The future of most altcoins are uncertain, but Ethereum is proven itself to be a solid coin with mass volume.
If you say Ethereum is next to BTC, it looks like they are both like kings and queens, 
if I think it is more appropriate to say Ethereum is just below the BTC, it means that there is no other Altcoin that is able to be second at this time according to volume demand and trade volume.