What grid sizes to use for non-responsive design?

Question

Design

I am a web designer and have not found among the many articles a clear answer for myself which options are preferable.
For example, let's say if I'm going to sell a theme on themeforest, what sizes should I use? And in general is adaptive or responsive better for this?

Answer 1

sitemaker.su/dizayn/sovetyi-dizayneru-ot-verstalshhika

Answer 2

Same as for adaptive, only your minimum will be roughly a fixed maximum.