Personalized gifts for any occasion will feel more special than something that's more generic. For a bar mitzvah, when a young man will be receiving lots of gifts, a personalized piece of Judaica is a sure way to make it fondly remembered.
A practical piece of Judaica with a name or monogram, like a kippah, kiddush cup or tallit bag, or a more ornamental item like a shofar or mezuzah with his name on it will make it one of a kind, irreplaceable, and cherished.