I know many will say the time ended, we must have bought before 15 days but I think this is the best time. Before couple of weeks ago, BTC was around $4k and which is why altcoins are overpriced in term of BTC. Now that BTC has gained price, altcoins price has decreased in term of BTC and now is the best time to pick your favorite altcoin because right after the BTC ride, altcoin will also follow the trend.
I ve been holdign for over one year the same altcoins. the past 6 months was the best period to buy. Even now with the curent price rises we are at the beggining of a bull market. As for what to get just the old solid projects like ETH, BNB, NEO, LTC, monero etc.