Everyone has done a good job covering the pros/cons of what you sacrifice at each level. I’d just like to mention that the specific classes can matter too. For example, I like multiclassing monk on everything because punching is fun. In a situation like that, getting tavern brawler at level 4 is my power spike, so I stick with the main class until 4 then throw some levels in monk. It’s possibly to find pretty goofy combinations between classes and only 100 gold to respec so there really isn’t harm in messing around and testing builds out.