Too bad we can't choose more than 1, or prioritize. My list (based on a combination of factors) might look something like this:
1. Blackcoin
2. Pesetacoin
3. Darkcoin
4. Fluttercoin

I'm surprised how little I hear in terms of development and promotion for litecoin. Seems like the only advantage it has is that it was among the first clones of bitcoin. If I could short it I would. Even dogecoin or mintcoin likely has more staying power than LTC.