Litecoin seems to be a good choice

It is good for both short-term trading as it likely has the highest level of volatility among major cryptocurrencies and long-term holding as it has shown consistent gains during the last 3-4 months. Well, all major altcoins have shown consistent gains recently (along with Bitcoin and partially being fueled by Bitcoin's spectacular growth) but let's not forget that Litecoin halving is just around the corner, so we should expect at least some hype before the halving followed by the supply squeeze soon thereafter and culminating with a refreshing change in price (not that Litecoin's price has been stale but you get the point)