That depends on how many days your boyfriend's birthday is. If you have enough time, you can consider making a birthday gift for your boyfriend yourself. Such a gift can best express your feelings and move your boyfriend the most. The gift itself also contains your love and blessings for your boyfriend. It is definitely the best birthday gift for your boyfriend.
If time is not very abundant, you can go out and buy some practical things for your boyfriend as birthday gifts, such as belts, ties, watches, razors, etc. Such gifts can reflect your concern for your boyfriend and are also good. Don't choose things that are too tacky. You need to observe your boyfriend's taste carefully.
If the time is not too short or too long, you can go to an online store that sells personalized birthday gifts to choose a personalized and creative birthday gift for your boyfriend. Boyfriends generally have never seen such gifts, which can reflect your feelings. I believe that it is definitely the best birthday gift for your boyfriend.