I have long term invested into Bitcoins, its seems like the best choice, the coin are the biggest and most well know, all other coins can come and go, Bitcoin will be there to the end, so I will hold Bitcoins for many years.
But I dont think Bitcoins are the coins that will give the highest return, but I see it as the saves investment I can do into crypto.
Other coins than Bitcoins will be better investment options for medium term period like 3 to 12 months.