A best friend message has more freedom than almost any other relationship — you can roast them mercilessly, get genuinely sentimental, or do both in the same three sentences, and it'll still land, because the relationship itself does the heavy lifting. The one way to actually get it wrong is writing something that sounds like it could've been sent to anyone.
Whether you go funny or genuine, the message that actually lands is the one built around something only the two of you would get — an inside joke, a shared disaster, a running bit that's been alive for years. That specificity is what separates a best friend message from a generic one; the humor or sentiment is just the delivery method.
If insults are how you two show affection, lead with it — a best friend message with zero teasing can actually read as oddly formal if that's not how you normally talk to each other. The roast works because everyone reading it (including them) knows it's affection wearing a disguise.
Some years call for sincerity instead — a hard year, a big milestone, a moment when you actually want them to know what they mean to you without a punchline softening it. This isn't a betrayal of the usual dynamic; it's using the freedom the friendship gives you in the other direction.
Distance is exactly where "we haven't talked in weeks but it doesn't matter" friendships get tested — a message that acknowledges the gap without apologizing for it usually reads better than pretending no time has passed.
If you want it to feel like more than a text, a reveal-style Interactive Experience or a Group Wish pulling in your other mutual friends can close the distance gap better than a message alone.