Here is a good source to decide which altcoin to invest in. I would never buy a dead altcoin with no development except Doge. Doge is unique and will be successful without much development.
Of course we have to choose an active altcoin before investing. At least have adequate daily trading volume. Price is not a problem, low prices can still be considered. Another thing to look at before investing is the developer's level of involvement in the project once it's developed, not a project that's just been abandoned.
I agree on that before investing we need to choose the active project with a active team, and active trading in market, many projects are being abandoned after they collect funds from ICO, so it is also important to choose a good and transparent team. Because if the team is not transparent it is very risky maybe the project is scam so we need to be careful.
All these active projects with an active team and trading in the market may one day cease to be active. Therefore, this parameter, as an activity, can't be considered a selection criterion. I will not say that it is completely stupid to invest in an inactive project, because this will already be an indicator that it is dead.
No matter how carefully you choose, investing in ICO is like playing roulette. If your bet is successful, then you will make a profit (if you sell their tokens in time). If you miss, then your money flew into the pipe.
Behind any seemingly good team and project, there can be a dummy.