I think investing in alt coin takes a long time. because the price when go to market first time will be very destroyed, plus dump from bounty hunter which become a problem. it would be nice to use the "just hold" formula of warren buffett for the coin that you think is good
Investing bitcoin and ethereum are most preferable for long term investment as it is already known by most. Aside from that, they havev already put a mark in the blockchain market because of its outstanding price performance.