Z-system lens recommendations

I wanted to know what people recommend as a starter glass set for a prospective new z6 owner.

Said owner had a d500 with the following lenses:

• 16/80 f2.8-4
• 70-300 (newer version)
• 50 f1.8
• 35 f1.8

For equivalent or better range coverage, and better sharpness, and without breaking the bank - what glass do people recommend?