only bitcoin and fiat or other investments such as gold,... because altcoins are too unpredictable to be considered as a good long term investment. the same goes for bitcoin to some extent too but the difference between bitcoin and altcoins is the fact that bitcoin has got the real world usage which altcoins lack. and that creates an ever rising demand for it.

the altcoins that are mentioned so far are all over pumped which makes the investment even harder. and none of them (except LTC) has anything good coming for them in the near future. so it is a safe assumption that they may fall.

so unless you can apply some sort of automation for your investment with stop loss then you are taking a huge risk.