I don't like the idea of going all-in on one cryptocurrency because I always want to diversify my cryptocurrency investment, that is the best way to decrease the chances of losses or risk. But if I were to choose only one cryptocurrency to all-in for 3 days, it would be Bitcoin but since Bitcoin already reached new all time high $9000+ and no guarantee that will continue to rise in the next few days, my other option is any top 10 altcoins from the market that reduced 5-15 percent of its value but I will check the news first and will look for the reason of the downfall, if there is no serious reason then I will take the risk.