On that note, Ogres and Chaos have really been the top armies in recent memory. Probably because of their popularity.
Do you have any experience facing 3-6 Stormfiends. I imagine that unit is fairly frustrating to face. You build a list with a bunch of synergy and interesting tactics and then they just pick 6 models that can tunnel and kill almost anything. That's a pretty simple way of looking at it, but it's somewhat true.
Not much you can do, especially in small games. Your best hope is getting a couple of cheap units to put around the rest of your army in rings (some people call it castle-ing up) they have to be 9 inches away from your nearest unit so with a meat shield or two can protect your better units then counter attack. Carnosaur bloodroar really comes in handy against units like that, first time i did it killed 1 stormfiend and the bloodroar made another 3 run away!
This is a good resource for your storm friends, Dealing with threats Other than that bring a starseer and make him reroll to see if they come up. I have only ever had that work once though.