i would recommend beside bitcoin are:
ETH and LTC
this is for a long term Hold plan , for this two are the next
big coin aside to BTC and much more improve and a few aspect
so considering to invest in these two is not a bad idea for
this two after BTC is with the crypto world for a long time beside btc.
i myself hold these two cryptocurrency and plan to pursue to HOLD
it on next 4 to 5 years or onwards for i believe on the project of
these two coin , and right now these two coin are gaining momentum
on a bullish pattern and it's going to establish a average graph sooner
which indicate as a good market for these two coin.
still do your own research on these two coin and other prospect coin that
you like to invest too.
you would like to do research considered always looking their price at
https://coinmarketcap.com/here they indicate the price and update it time to time.