The thing is, the two coins your mentioned above are more of long term projects than short term ones, but it doesn't mean they can't be a good choice for the latter, it all depends on the amount of your investment, and it's much better if it's a fairly large sum so your ROI can be something worthwhile. Many altcoins are short term projects cause they have the nature of pumping and dumping, thus investors choose them for the short term and hope to be lucky to sell when they pump, thus sort of investment carries a lot of risk, but it can be profitable sometimes if you're lucky to sell at a good time. But overall Bitcoin and eth should be your best and safest option both for long and short term investment.