3 1/2" of XPS foam board is about r17.5.

FG batts will work fine as long as there are no wall leaks or flooding. (A safer method would be to use rockwool, as water will not affect it.) To avoid moisture problems from minor flooding, the 2x4 plates should put on top of strips of XPS (extruded polystyrene) or at the very least on top of 6 mil poly strips.

As long as the foam is thick enough to prevent a condensing surface in the wall your approach will be fine, provided your basemen is never subject to any water intrusion. Using all spray foam or using rigid foam board would be safer below grade.

Our neighbors just finished their basement & they now say that they regret getting the spray foam. Their basement is now even warmer than upstairs & they are not a fan. We are just using the fiberglass insulation, but I will look into the rockwool as stated above. We are also not installing insulation all the way down to the floor in case of water. Our contractor suggested stopping it 12" up.

we have to use pt wood for bottom plate

Must be a local requirement.

If that's the case, then no need to bother with foam.

I never use pt in a home as the cutting and fastening creates hazardous sawdust that occupants and carpenters could do without. I use light steel--neat light and clean.

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Our neighbors just finished their basement & they now say that they regret getting the spray foam. Their basement is now even warmer than upstairs

That illustrates how well the foam is working, conserving the heat that was radiating to the outside.

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We are just using the fiberglass insulation, but I will look into the rockwool as stated above.

Fiberglass directly on the basement wall is a recipe for mould. Instead of expensive spray foam, you can attach XPS (extruded polystyrene) boards directly to the foundation wall, followed by fg or rockwool batts.

This proprietary system combines the elements of moisture impervious high R Value insulation, air sealing and no thermal bridging into one "package" Video.