I think BTC by a longshot, but atleast with ETH deemed not a security it has the same potential without legislation getting in the way... just when I look at coinmarketcap at "currencies" vs "smart contracts" I see eth with massive competition right behind them and wh en I look at Bitcoin, all I see is Litecoin (which bitcoin is adding lightning network) and Monero (which is the alternative private version of currency). Ethereum's biggest problem is its scaling vs its competitors knocking scaling out of the park.. adoption will get you far but when the network starts getting clogged down the most its used in the future, it could be a major problem.