That's a great question, and it really depends on the source material and your listening setup! For music, I usually aim for 192k or 256k MP3 quality. I've found those bitrates offer a good balance between sound fidelity and keeping the file size manageable. Anything lower than 192k tends to lose some of the musical detail, especially if the original video's audio was already good. If you're converting videos, I've had good luck with services like
youtubetomp3 because they let you select your preferred quality level easily. It's safe and reliable, which is important when you're frequently converting files; you just paste the video URL and choose your desired quality. For spoken word content, 128k is usually perfectly fine and saves a lot of space.