No to Stablecoin and Sexcoin. I have lengthy reasons for both, especially Sexcoin.
I'm not sure on Aliencoin. Don't know much about it. But if it goes like 42 coin, I suggest being one of the very first to invest in it and then sell pretty much immediately when it gets on an exchange. Those guys are better for marketing/branding than actually developing a coin (notice how many projects they're trying to handle rather than focus on a single project).
If you don't believe in cryptos medium/long term, then I suggest looking at OP's data. It indicates that QRK, Zeta, IFC need barely any money daily to maintain their value. Coins like Doge, if they lose interest, even if investors don't sell a single coin, miners will drive down the price unless 1.3 million dollars enter the market.
If you believe in cryptos, invest in the coin that has functional features that you think will separate it from others.
If you want to be safe - go BTC (lowest risk, some potential for growth), choose either LTC or Doge (personally not a big fan of these, but high growth potential), and choose QRK or another CPU-mined coin (personally I think a CPU-mined coin will be the future. QRK is a good medium term investment, still not sure how it will end up long term. But its got community, transactions 12x faster than btc and 8x faster than ltc, and only needs 800 new USD per day to maintain its value).
As for making money quickly and with a high return, follow coin launches and see which one is getting hype based on a meme or a feature or a developer. Buy in fast, and sell fast, because it takes a TON of effort to become a top 10 coin.
sexcoin failed to deliver on their promises