Make a decision
Basement furnace versus mechanical closet
One scope
Basement access may allow space around a cabinet and trunk ducts.
The other scope
Closet access can limit panel removal, filter reach and safe work area.
A concrete example
Removing a blower from an open basement can be simpler than removing it through a narrow closet door. Ask how the contractor will access the actual unit before comparing labour lines.
Which question settles it?
Ask how access affects the quoted labour and what building approvals are required.