I think I've tried a million strings so far, and the Slinkies are just the perfect balance of what I look for in strings: they sound great, are extremely sturdy, and stretch so well simultaneously.
As for longevity... Well, I have a habit of changing the strings at least every two weeks. Even if not too corroded, the grease and sweat from the fingers don't feel too good and degrade the sound, especially in the summer. If you like cleaning your strings - go for it; I prefer just changing them. However, it's any sting brand, no matter how expensive they are.