Here's a link to the player stats; slide a bit down from the top for Blasters. It's a year old now but it has some interesting info on popular sets and combos.
It seems like people like to have themed combos -- fire/fire is the most popular blaster combo followed by energy/energy and archery/tactical arrow. Sonic is the least played primary and ninja training is the least played secondary. At that time, there were only 2 AR/Electric in the entire game, indicating perhaps that those two sets don't pair well.
On the other hand people took that list and sought out combos like that and found a way to make them work. For example, I made an AR/Traps Corrupter as those were the two least played corrupter sets.
So while there are certainly sets that play well together and have synergy and become popular FOTM, you can also find oddball combos and make them work. They may not be able to solo a +4/x8 ITF with no temp. powers, inspirations, or deaths, but they can be tons of fun and hold their own solo and in teams.