For me, Etherium, Litecoin, and Monero are the best three altcoins because these three has a good blockchain technology, they are also popular that makes each of its xommunity larger. And community of a crypto is important because it provides the demand for a certain coin, and since crypto are dependendent of the market demand in terms of its market value, a crypto community is surely important. And remember, the factor that made Bitcoin to be the no.1 crypto for a long period of time is its large community.