Here is my own investment advice but not to be taken very seriously because anything can happen in crypto space...
I think the best altcoins you can invest on in crypto space are bitcoin forks, they are very responsive to bitcoin movement and their All Time High is very good too, one for thing is these coins have their halving coming this very year as well
1. Bitcoin Gold
2. Bitcoin Diamond
3. Bitcoin Cash
4. Lightening Bitcoin
5. Bitcoin Private
These coins have their use cases and they offer better performance compare to their king ( Bitcoin ) and their team are very active as well, looking at the past chart of Jan 2018 these coins ATH are massive, buying now means buying at extremely cheap price, they are jumpy, active , responsive to Bitcoin Movement and their Halving is happening this 2020 as well.
Please do not hesitate to do your own research and go through their whitepapers, these are no new projects, they have proven their existence already, thank you
For this situation you can think that this all Bitcoin fork is good profits, when we will talking about long term there will be a problem. To earn some profits in this Halving time you can make investment in this fork coin but not for long time. Without top coin I won't suggest all of this fork coin.
Some of them are already top coins without any doubt, but I still believe that everyone should know what he/she wants. Investing in bitcoin does not mean you are going to profit from it, let alone the forks of bitcoin. Bitcoin Cash has really grown, but I do not know much about other and most times, whenever there is an upward movement in the market trend, it tends to grow at a significant are and on its own, it is quite very responsive. Yet, every investor should chose coins based on the personal perception or conviction they have about it and not what people are saying.