The best altcoin you should buy are Near, Dot, Sol. The reason for my suggestion is those coins are building a platform which similar to ETH, BSC and we all know how ETH, BSC price move. So you should consider to add these coins into yours bags and keep hold them for at least few months before next altcoins season. 
Yes, all Altcoins are good to consider now, but will this year still have the next Altcoin season? if so, in what month it will happen so that everyone can wait for it to be the basics, because now the market is still not fully recovering.I think nobody knows when will be the next Altcoin season but I believe it will happen again. For now, all we can do is to buy more potential altcoins like ETH, XRP, BNB, ADA...etc as long as we have capital to buy.