In the really long-term even Bitcoin might be gamble (just imagine the decreasing block reward... PoW might be at risk).
I prefer alt coins that seem to deliver something really important.
As of now I see that especially at LTC, PPC, NVC and XPM (and maybe QRK because of its different hashing approach)
All other alt coins are more or less copy-cats with adjusted variables.
Thinking twice I come to the conclusion that QRK fits in the row of LTC, PPC, NVC and XPM.
But no one knows which one(s) will succeed
edit: wait a second - almost all QRKs are already mined? Are transaction fees distributed as rewards? We might soon see whether the network can be sustained or not once 247 million QRKs are mined and "only" 1 million per year follows...