Overall I prefer the Overlord too.
Proplem is: you need fighters, and this kind of screws up fleet building.
You are either stuck with the costly paperweight Dictators or the super slow Emperor that takes a big share of your deployment points. Or take no fighter and get stuck in a uphill battle versus quite a few, very popular strategies.
Mars still got respectable long range firepower, can keep up with the rest of the fleet, and Nova is actually pretty good when taken en masse especially against few, but very powerful strategies IN struggle very much against (Ork mass escorts, Chaos carriers and Eldar... well... everything Eldar-related).
Also, for bonus points, which cool-named, top-dps, single-offensive-upgrade-dependant cruiser carries the Nova?
I tried, really. Brought a ram+torp based fleet with Dictators and Overlords up to lvl 8 and then some.
In the end tho, I feel 3xDominator + Mars is the best we have got. And that's saying a lot.
Not saying other strategies are not viable, it's the wierd list sinergies (or rather lack of thereof) that make me go "I actually can't round up this strategy", forcing me to make inefficient decisions or just glaringly incomplete setups.
Like in 3.5 D&D when a useless prerequisite Feat, together with how scarce such resources are, ruins your character plan.
I am alive and you are all dead
Leveling up Chaos: