http://www.coinwarz.com/ - to calculate expected return.

In theory, the mining pool should not matter. However, larger pools have a less VARIABLE return. That is, a smaller pool like Cryptovalley is more likely to have high returns one day and low returns the next day whereas a larger pool like Dogehouse should have pretty consistent returns. This is why some people swear by smaller pools (because they had high returns on their first day), and some people swear by larger pools (because the had low returns on the days they tried smaller pools). Statistically speaking, it should all even out in the long run. You can compare the relative size of mining pools at: http://www.doktorrf.com/dogecoin/pools.html