Any suggestions of racing series more interesting than F1? I tried to watch Blancpain, Super GT, IMSA, Le Mans - all of them seem to have almost non-existent level of overtaking (even worse than in F1 imho)
Try watching rallycross [0], it has lots of action. Depending on your location you can see parts of or all of the races live on YouTube. They have also started with an electric series, project E, that looks promising.
Second this. Not sure why people watch F1. MotoGP is infinitely better and in fact, it seems to just get better each passing year! The secret is that it's "90% rider" and "10% machine".
I really think "it's 90% rider and 10% machine" is a big exaggeration in MotoGP. Even Marquez is not going to win a race on a current generation Aprilia, and I'm not sure there is anyone other than Marquez who can win races on the current Honda.
edit: regardless, Dorna has done a great job making MotoGP competitive and MotoGP has to be at or very near the top of the list for the best racing on the planet.
I'm a big fan of rally racing. It's a fundamentally different model of motorsports -- driver vs. course instead of driver vs. driver -- so there is no overtaking at all, but the action is still far more exciting.
Formula E, Formula 2, and IndyCar have been producing better on-track racing than F1 pretty consistently — but they’re all spec series, and engine/chassis development is strictly limited.
Standard season of WEC tends to have more overtaking than Le Mans itself. For interest rather than overtaking, WRC is obviously well up there. And if you really want no-holds barred overtaking, anything on the BTCC schedule should be well up there (well, except F4 and oddly, the Porsche Carrera Cup) - Ginetta Juniors is a particular highlight.