I`m looking into mining as well. Once I buy mining hardware, I have my eye on the bigger pools cause I read up on getting paid on error`s or work already completed.
And the odds to find a block is quicker I heard. I feel like in some sense its a monopoly... all the smaller pools are going to slowly be smaller since they wont get that many blocks like the bigger pool does.
Your expected mining revenue would be the same (before pool fee), though the variance will be smaller if you join a larger pool.