People over-think Raven’s capabilities. She’s a glass canon. She has a number of capabilities, mostly not offensive in nature, but she traditionally is easy to incapacitate if overwhelmed physically. She has good defenses, but she’s not as strong as popular media has made her seem to those who’ve limited comic readings. Honestly, for the first few decades of her publication history, she was a “support” member of the team, largely not participating in battles (heck, she was even pacifistic and didn’t actively fight during the better part of the first decade of her existence).
Starfire is swift and strong. If she can get to Raven, one blow should stop our beloved mistress of magic. Undoubtedly, Raven could win some scenarios. But I do believe Starfire could perhaps win more of the many ways this could play out—at least with Raven in her right mind and standard set of abilities (which have limits compared to when she’s given into the Trigon influences and becomes more powerful, even physically).