Nobody did yet a real Full Frame equivalence of both the focal length AND aperture. So let me do this: The GFX lenses have a bit more than a 1/3 stop advantage. The below equivalence numbers are rounded:
23mm f/4.0 in Full Frame 18mm f/3.2
32-64mm f/4.0 in Full Frame 25-51mm f/3.2
45mm f/2.8 in Full Frame 36mm f/2.2
63mm f/2.8 in Full Frame 50mm f/2.2
110mm f/2.0 in Full Frame 87mm f/1.6
120mm f/4.0 in Full Frame 95mm f/3.2
Designed fast lenses for medium format is quite challenging as they tend to become very big. Based on those conversion I would definitely go for a 45mm lens and the 110mm lens. And you?
UPDATE: Thanks to Mike for the slightly corrected aperture info!