I'll admit I'm somewhat biased against Bun, but I'm honestly interested in knowing why people prefer Bun over Deno.
There's certainly an argument to be made that, like any good tool, you have to learn Deno and can't fall back on just reusing node knowledge, and I'd absolutely agree with that, but in that case I wanted to learn the package, not the package manager.
Edit: Also it has a nice standard library, not a huge win because that stuff is also doable in Deno, but again, its just a bit less painless