You can trade any altcoin that has liquidity. If you want to pick, I will recommend the current trending coins to trade. Remember you're not Investing here but just interested in the profit the coins can generate therefore following the trend has to be one of the ways to achieve that. Coins which large marketing stand a greater chance of giving huge profit day trading due to the volatility of the market.

The ups and down movement of the market makes it a perfect market to trade, you have to be careful though has the altcoin marker js very unpredictable in that you can either lose all your capital from a rugged pull or exist scam scheme by a project developers.