I really liked Sonya when I played her, her damage output is pretty ridiculous I found when you use Wrath of the Berzerker and start spamming those smashes and shit. Also pushes crazy fast if people decide to ignore you because "lelz sonya is pushing, who cares". Like you can keep WotB for a stupid amount of time and you spam those 600-700damage line aoes every second or so, you'll demolish an entire lane in like 40seconds if left alone at higher levels, even specialists for the most part don't push as fast as her.
Her main issue I'd say is she's considered a Warrior for the game balancing purpose in QM, when really she's a tanky assassin. In HM I guess it really depends on how you build your team but it follows the same principle, you can't have her as your only initator cause she's pretty shit at it.