So I get the impression that a lot of people don't really get just how different the factions in the game are. Which is why we see a number of threads that seem to keep saying that Dwarfs or Empire are OP.
Here's the thing that you really need to remember in this game; this is not a historical Total War and the differences between factions are therefore far more pronounced and significant than ever. The Dwarves, Vampires. Greenskins, Empire and Chaos are all completely different and will therefore have huge advantages over the others. Every single faction is (especially compared to historical Total War games) OP and is supposed to be OP.
Let's take for example the whole Dwarves are OP/ Dwarven ranged infantry is OP issue; the thing about the Dwarves is that they are all exceptional melee fighters, therefore even a decent dwarven melee fighter will be (and should be) able to hold their own against the melee fighters of other factions. You can not expect to assault the Dwarves from the front with basic units and not get slaughtered, and there is absolutely nothing wrong with that, it's working as it was supposed to. If you want to face off against the dwarves as the greenskins, you have to use the units suited to the job; your Ork Boyz are cannon fodder to Dwarven units, bring one of the many monsters you have (which have also been called OP) or Doom Divers if you want to break a Dwarven line, otherwise you flank using your Big'uns or Trolls, amd please do not expect your throwaway cavalry to have a great effect on the Dwarves. Additionally, you will (barring any huge blunders on your part) generally outnumber your enemy; that is in fact a significant advantage and should be used appropriately.
The other example is the Demigryph knights from the Empire; considered OP for it's massive effect. What did you expect, it's the top tier unit for the Empire, who are supposed to be the most versatile of the lot, not to mention having the best overall cavalry. The Demigryph knights are a representation of that; they are the very best cavalry that the Empire fields, being seated on monsters themselves. Want to counter them, consider bringing armour piercing weapons to the fight and flanking them with it. Don't expect them to behave like normal human cavalry.
Another says that Mannfred is OP; he's a wizard and a vampire whose death kills his entire army; yes he's good at both magic and melee and that is how he's supposed to be. He is not a dedicated wizard or any other kind of normal unit, he's a legendary lord and therefore presents a unique case that has been handled appropriately.
And then they call Grimgor weak. He's not weak, he is in fact a pretty terrifying enemy all on his own; consider not charging him frontally into a Gun line or cannon fire though and you might get to see how good he actually is.
And one last thing; Bretonnia isn't a fully fleshed out faction yet, and it hasn't been updated on the TT for a long time. So please for the sake of sanity wait for it to be finished before making any judgements on it, and try to not expect the Earth and the Sky from Grail Knights.