I invest to the ranked coins but not go for all because I choose the coins only with big potential in the future, so I'd say if I also invest to the non-ranked coins which I research before invest.
Most of the cryptocurrencies I have in my portfolio are the top-rated altcoins (TRON, Stellar, DASH, Litecoin, Ethereum). Meanwhile, it does not mean that I ignore the other alts. I hold Credits, Napoleon X.