Bitcoin was the first cryptocoin and is the preferred coin by most of people.

Litecoin and Dogecoin have a wide community adoption. There are lots of people that uses them (but not as many as Bitcoin).

Percoin doesn't have the same community support than the previous coins, but It have a different algorithm (It's like NXT) and It could increase their usage, because that algorithm is very efficient. But I think that It wont replace BTC, because if that algorithm is enough secure, Bitcoin code could be modified and adopt it.

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Remember that Dogecoin doesn't have a fixed amount of coins. The number increases with the time, so It can have inflation. Bitcoin and Litecoin have a fixed amount of coins.

I use Bitcoin for savings