Does anyone know of resources comparing the GPM of various tub fillers?

We have a big tub coming and I'd like to find something with a high rating... We have plenty of pressure and can rough in whatever is required.

The tub is basically freestanding, so I would prefer a freestanding filler or something like the Geberit Cascading Filler.

The current tub has a shower valve installed in the ceiling above it, so I could convert that for a filler, but I don't know that the ceiling fill look is really my thing, unless it had a great purpose.

Thanks