With airlines worldwide, the general concensus is that 3-3-3 is the preferred configuration. However, a number of mainly American airlines still maintain the 2-5-2 configuration and certain FFs like that very much due to the 2 seat window pairs.

Generally, if the average load factor is <80%, 2-5-2 is better.
If the average load factor is >80%, 3-3-3 is better.