You are approaching these investment decisions correctly! Think about what problems they solve before you buy.
LTC solves BTC's network fee and leadership problems but there's no telling how long that will remain viable as a way to increase its value
ETH solves network implementation and contract fulfillment problems that it's a bit trickier for BTC to solve.
DASH solves capital liquidity problems among other things, and makes it easier for end users to use DASH as a currency.
IOTA solves internet-of-things resource exchange problems, redundancy is improved thanks to the tangle.
These are the only ones i'm familiar with enough to speak on. Good luck!
If someone tells you something is good and they can't tell you why, don't listen to them.
i think this is a good answer for your question,don't ask recommendation from who cant explain that