Here’s the list and video of the top 5 DPS classes according to Ziqo, Praii and Hotted.
#5: Death knight, either unholy (sustained) or frost (burst teams)
#4: Shadow priest. Major weakness if when facing melee teams that train you.
#3: Windwalker monk. Potential one-shot within their stuns.
#2: Fire mage. Has lots of instants for countering melee plus lots of crowd control.
#1: Rogue. Outlaw if running with a burst comp like a death knight. Subtlety otherwise.
Watch the video for more detailed explanations.