It would be VERY helpful, if you would tell us, which currency you want to mine.
Not every pool supports every coin.
Without more infos we can´t help you.
So, I don't have a physical miner but I wanted to explore NiceHash. So, for that we have to join a mining pool then rent hashpower. So, in this case which pool would I join? My criteria would be the most profitable, stable and reliable mining pool.