Altcoins are known for any kind of accusations you can mention but where there is bad eggs, sometimes you can also see some good eggs in there. Some altcoins for years are known for prioritizing their community, the team does as exactly as they say and they are decentralized to some degree even though they can't be like Bitcoin.
If you do your research properly, there are some altcoins that are worth investing. Coins like BNB, hype(this one don't play with the community) and many of them but there is nothing like best altcoins. Make sure you diversify your portfolio as possible and more of your investment should be on Bitcoin just for safety precautions.
Yes I agree with you that you can't totally generalize that all altcoins are one as there are some few once that has shown prospects in the few past years but let face fact the truth is that altcoins are not trustworthy and should not always be prioritized as an investment options because it's too risky.
So sticking to Bitcoin should be the best as it's more durable and reliable than altcoins which are pron to fail
Altcoins have categories and for that reason we have some that have higher demand and working ecosystem those types of coins are not so popular but we have a few of them which are known to the entire market, but then we choose to make emphasis on Bitcoin since Bitcoin investment offers us more confidence and less risks compared to altcoins.