Heros for vanquishing

Okay so after I finished the campaigns, I found myself wishing the vanquisher titles. So I started to vanquish. However soon enough I found out that well my heores are lame.

Now someone told me to invest in a good 7 men team. My question is which heores should I get? Should I get more Mo, should I get more E? More N maybe?
I just want to vanquish without being constantly stressed.

If anyone could also post some builds along witht he advice I'd be really grateful.

And btw I read guides and stuff. I am just not sure what to get since there are so many options and since I am quite new to the game I really need some pointing since I don't want to waste valuable resources.

Thank you in advance for your feedback.

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