I happen to be co-leveling a Scrapper and Jedi Shadow at the moment. Yes, both are stealth classes. My opinion is slightly incomplete as the Scrapper is 23 and the Shadow is 17. Scrapper at this point definitely has greater CC abilities and I feel like I have more options in a fight. That said, as of level 23, I am having trouble ever getting the medal for doing 2.5k damage in a single hit on the scrapper. My Shadow does it regularly. Even so, I don't see my Scrapper doing significantly less (if at all less) damage during the entirety of a Warzone.
Both are fun, which is why I'm playing both rather than choosing one.