Well all investments are asset on their own. However, asset is the term commonly used for long term investment. So for long term hodling you should go for some giant coin whose much potential is yet to be harnessed. Bitcoin must be your primitive choice, however, Ethereum must not be avoided as many experts say it could go $1000 till the end of year.
Other coins like Waves, Strats, Lisk, QTUM too have bright future ahead but just keep in mind not to invest in hollow coins whose price goes up and down significantly just because of pump and dump.