Have spent most of today exploring the various current version of Utility Tracks in 2021 and would agree that the full RT picker is the best option.

Like Rustyspoon I will use a style as a start point, then choose RTs using the Picker. I am aware of the other filtered pickers, but only occasionally use the Best Chording when I need an acoustic guitar.

As to the idea of using a "legacy" track then copying to Utility, that is at best a time consuming work around that should not be considered as an option.
While the momentum appears to be still on for Utility Tracks now is the time to integrate them into BIAB properly (IMO that should have been done before launching, but what's new there?)

As mentioned in a thread a few months ago the RT picker and Drum picker should be combined, at the moment I see no options to generate drums into a UT.

Vintage