Of course from all alt crypto that exist, Bitcoin is the best choice to invest with it (of course fro a medium to long-term), if hold some coins that are too low from ICO price that not having any development in their product, then better sell ir right away and get some btc or eth.
when in a position of upward movement in bitcoin it might be better to save bitcoin. but if the trend is on an altcoin then choosing etheruem or other assets is better. choose assets that might experience the fastest growth.