what's your favorite chess opening which helped you to improve at chess?

Also the Italian.

For me it was 29 years of the French Defense.

Fried Liver is good for climbing at low elo because 99% won't see the fork and will lose the rook which gives a pretty good advantage

RL and KID: highly varied complex positions, long strategic lines, & for KID how to tap into potential energy of cramped positions, for RL how to squeeze a small plus .

Now there is more thy than I can keep up with for KID so I only play it in blitz games. I still play RL as white as ideas & experience are often enough in it.

bill

Giucco Piano Game Main Line.

Italian

Idk what's my favourite, but I'm definitively wary about the Caro-Kann. I had the marvellous idea to begin my learning with this complex defense and to abuse of it...but mistakes also lead to improvements !

I dont know any chess theory except E4

Queens gambit for sure, and pirc for black

Sicilian