Definitely Stratis I bought Stratis at 3k sat and it went to 460k sat max, although now is only 58k sat, it is still 50x in btc value, and 500x in fiat. Long term holding!
There are so many altcoins that has shown huge prospect this year and great chance of performing and I believe 2 years is a bit long for them to even do better. STRAT is one for sure, and I am really looking at this coin for longer prospect among others. The year has been tough though for some of this projects with BTC's development and anyone wise would really use this opportunity to stash some of this coins.