Basically Fighters have a swell time from 1-12. It jumps off into Wizard at 12 because at that point the Fighter progression slows down a bit; you'd have to wait all the way to level 20 to get another extra attack and that XGtE War Magic school has a lot to offer both in the short and long run.
There is one common mistake I see with EK that gives some people a negative experience with them: They somehow get it into their head that they should be using spells like "Scorching Ray" that rely on their second-rate Intelligence scores. Don't do this! Look for spells that don't rely on your Intelligence score, and ones that augment your martial abilities rather than replacing them.