on this very day, many may no longer see 2017 as a great year for cryptocurrencies but to me it still is because 2017 set the record in terms all time high which has been broken to (16/12/2020). This very later part of 2020 for now appears to be the the golden time for crypto especially bitcoin.
I am more focused on the golden year for Bitcoin. Not for other cryptos, since the one that experienced an increase to reach the new ATH is Bitcoin, maybe LTC will experience it too. But altcoins are not experiencing impressive peaks. just experienced a general increase. So the best year for bitcoin is 2020.