Murat vs Davout

They are on different style IMO. Davout strong because of Inf killer, critical and chance for double attack, his station also really good in city, stable ... But Murat has higher base atk, 100% make full damage (except damage reduce by armor type), plain fighting is very good and cavalry commander has 3 grids range of effect, suprise atk is still unknown now. In damage focus Murat lose a bit but he is more versatile

In EW6 it is more difficult to choose the best one. As in comparison to other games Gens are quite similar and sometimes have same skills, like Washington and Bismark for example.
What I want to mention is that choosing another gen You need to anticipate Your whole team and gens You already have. For instance I have infantry and artillery commander with plain fighting in my team, so definetely I don't need it witb my cav gen as I simply won't be able to utilize it -- there are no spare plains for all of them
Another one: if I use Blucher I don't need another cav gen with cav commander. So I don't need Murat again, as for my team he has plenty of "uselles" skills.
In the team of another build he wil be a world class monster probably.

There is no universal answer for "who is the best one?"

It appears Murat Cavalry Commander (just like Massena and Karl  Infantry Master) is actually a self buff on top of being a team aura buff so in effect it's like a (not percentage based) +20 attack power that works on any terrain so a fantastic skill in a Zerg but also great in solo.

Still, I got Davout instead because I really like Tactics Master it's so great for taking cities fast or laying down double damage on say an enemy unit that's attacking your artillery. That skill is not supper reliable but it triggers enough to make a difference.

If the leaked patch notes are for real the meta may switch at least somewhat from infantry to cavalry in which case we will probably need 2 cavalry commanders anyways.

I am thinking about Karl instead of Washington for several days already. Massena would be great, but lower stat in addition to low max Title - Prince (-18 battle ability) makes Karl much more attractive.

Regarding stacking of the aura skills. Everybody knows I am fond of it in EW5, but in EW6.. I doubt stacking will be possible really often. It's another gameplay. A lot of Your units, a lot of enemies, different terrain. I would prefer direct action skills instead of looking for stacking of the aura. Will have 1 gen with aura skills for each type but that's it I think.

yuanzhong, Are you sure? I though I seen a power increase when I upgraded my skill, could have been wrong though I didnt take a screenshot. I'll double check next time I upgrade the skill.

andrei, Right on,actually I was thinking about Massena or karl as well but yet still want Washington.

Let's not forget how useful it is in naval battles ( tactics master )