Depends on your mining plan. Do you want to mine on a multipool and get paid in BTC? Want to mine on a multipool and keep the mined altcoins (to trade/sell at better rates/keep in wallet)? Do you beleave in a certain coin and want to mine this one? Or just maximizing your mining profit, no matter which coin(s) you mine and get?
I myself didn't mine their as it doesn't suit to my mining plan.
I just want to get the most profit and sell at the end of the month. Right now I'm mining on https://www.multipool.us/
In this case (Multipool.us is in my opinion not the best pool for GPU coins) I'd have a look at ipominer.com and nicehash.com. Nicehash might be a good solution as they rent your hashpower to other miner, pay out in BTC and, depending on the rentals, you often get better profits then mining coins yourself (check their profit stats).