I recommend to go for the promising one. Maybe it will look expensive at first sight so go and check the price of BTC, afterwards all altcoins will look very cheap. In altcoins, my first recommendation will be none other than ethereum and the reasons are very obvious. It is at the top, has good community support and produces more profits than any other altcoin. After that, monero,waves, LTC, neo, etc, ripple all show some potential of growing.