bigger caps like BTC & ETH are pretty safe. If you wanna speculate there is so much to choose from.. low cap projects as AION, NULS, SKY def have my interest
I would prefer to invest in btc and eth now. some altcoins will grow very slowly in slow-moving markets. but btc and eth will quickly rise when the market starts to rise. you can try that, besides eth and btc investments are very safe, these coins will never disappear, but other altcoins may be lost from the market.