Not every project is worth the investment. It is necessary to assess the potential of the technology and the specific use case. Those are basic and essential issues. If you do not satisfy the above two basic problems, you should not invest in them.
It is also important to assess the market capitalization of each altcoin relative to their value. I like the trading philosophy that goes like this: "It's not the good stuff that's a good price to buy, and the bad stuff that's bad to buy." It is important that the price is good.