I may be in some aspects old fashioned. For example, I like to have my music locally on the devices I am going to play them at. So, I am grabbing my CDs and collecting everything as MP3s and Flacs on my hard disk. Then, of course, I have to deal with the MP3-tags, especially unifying them across the files. This is something, I wouldn’t need to bother if I would use an online service. Whatever.
After some try and error, I finally came across Mp3tag. It works and is nice to use when you are editing multiple files at once.