The Raptors have DeMar DeRozan as well. With him and Valanciunas they have two borderline All-Stars 25 or under.
They also have a couple of intriguing prospects like Terrence Ross, Bruno Caboclo and Lucas Nogueira in addition to their 1st rounder this year.
Finally, they are a playoff team in a weaker conference run by a widely respected front office. I can see their appeal.