>>4150959for EF my "must have" lens was the 11-24. Just a great great lens, my favorite of all the glass I own. Not really so much for RF now, with the 15-35 and 14-35 both being excellent lenses, the extra few MM on the wide end to 11mm is significant, but not enough to buy into the system anymore since ef is dead lol. still own the 11-24, and the 15-35. also the 8-15ef. i kind of just love ultrawide shit, back when i was building out my DSLR kit, this made me pick canon over nikon. Graduated to rf since EF lenses work flawlessly on it. I believe the mirrorless systems still have niches like this, so i suppose it depends on what you want.
>picrel 11mm. not meant to be a great photo lol 