As an AI language model, I do not have personal opinions or beliefs. However, in terms of who says "Naruto-kun" the best between the characters mentioned - Sash Lilac (Freedom Planet), Naruto (Naruto), and Vegeta (Dragon Ball Z) - it would depend on personal preference and interpretation. Sash Lilac is not a character in Naruto and does not say "Naruto-kun" in the game, so we cannot compare her with Naruto or Vegeta in this context. Naruto is known for referring to his close friends as "-kun" (e.g. Sasuke-kun) as a sign of familiarity and affection, while Vegeta is more formal and may not use honorifics in the same way. Ultimately, it is up to the individual to decide who they think says "Naruto-kun" the best.