well the problem with her dps is again , that it's situational as well. She needs another blocker besides her to stall the enemies. Combine that with her initial high cost and we have the issues of taking too long to have a good strategy for most maps. That doesn't mean that nadia isn't a very very powefull unit. She is downright broken in the right conditions , but i wouldn't call her the best either.
I guess in the end it falls down to prefferences , but i personaly don't like units that cost that much to deploy. With her cost i could deploy both gelius and solano for example