I really want to like Bun and Deno. I've tried using both several times and so far I've never made it more than a few thousand lines of code before hitting a deal breaker.

Last big issue I had with Bun was streams closing early:

https://github.com/oven-sh/bun/issues/16037

Last big issue I had with Deno was a memory leak:

https://github.com/denoland/deno/issues/24674

At this point I feel like the Node ecosystem will probably adopt the good parts of Bun/Deno before Bun/Deno really take off.