Real use cases plus real life working products, let these two be your main focus when picking altcoins to invest your money on, do not listen to those saying 'dump altcoins for bitcoin' when you are holding solid altcoins
Altcoins hasn't impressive the community for the past 22 months so you can understand why majority of the community members are advising to dump altcoins for bitcoin. Although the cryptocurrency market is very unpredictable so the final decision should be yours to make. Invest only money you're ok with lossing but don't invest with the mindset of losing. Always own some bitcoin but don't underrate the altcoins.