https://www.techradar.com/news/best-canon-lenses-ff

The sheer resolving power of full-frame Canon EOS bodies like the EOS 5DS and 5DS R, with their 50.6MP image sensors, demand the utmost sharpness from lenses, while even the EOS 5D Mark IV and EOS 6D Mark II have fairly high megapixel counts, at 30.4MP and 26.2MP respectively. But there’s more to a good lens than just its ability to resolve fine detail.

Handling is a key factor in how a lens performs in real-world shooting. You’ll need fast and accurate autofocus, to ensure that you nail defining moments in anything from a fleeting expression in portraiture to action sports and wildlife photography. In handheld shooting, meanwhile, effective image stabilization can make an enormous difference.