The internet is rife with opinions on this one! We do a 50-50 split for a reason.
Gi emphasizes a more distanced guard game, and the gi can be “training wheels” for developing tension (push and pull control). You can then apply this control in both gi and no-gi training. No-gi emphasizes a more butterfly and chest-to-chest game, helping develop pressure and lifting guards.
Both are highly valuable. To create well-rounded grapplers, we train both!