Being on the top 10 cmc is an example of a coin that we must have for our long-term investment. this is something that every investor must prepare in cryptocurrency
Buy the top 10 cmc tokens/coins is the safe one but if OP want to get a good profit, he can try to gamble invest and buy a bulk of token that not popular. Find the good one first that have a good future. In my opinion you can buy UTNP/UTN (Universa) because i think this one can go big in the future.
You are right, we should be able to choose what type of investment is the best; for the medium term (3-6 months), or for the long term, 6-12 months. The top 10 CMCs are categorized as safer, and rank 100 - 200 I think is better for the medium or long term.