If you're good enough, Tracer is by far and wide the best DPS hero in the entire game. She has it all: high burst damage, great mobility, the ability to escape, as well as a tiny hitbox.

While someone like Genji has to risk their life with every single kill (dash is used for both damage and escape), Tracer can use her Blinks to get into an overly aggressive position and then bail out with Recall. This might not sound like a big deal, but when you consider how much higher Tracer's DPS is, it becomes quite obvious why she's on just about every single Overwatch League team ever.

Another big difference is that Tracer isn't reliant on her ultimate to do work, whereas Genji was intentionally designed with 'weak' shurikens as a counterwight to his great ult. So while Genji can pop off and kill an entire team, Tracer can create pressure and get picks much more reliably throughout the entire game, especially against support heroes like Zenyatta that are easy to one-clip.