I can only make suggestions based on the three kits I have experience with

Plywood: Firewall, Fuselage Doublers, Formers, Wing Joiners, Servo Trays

Basswood: Main wing spars, servo mounting rails, landing gear blocks

Hardwood (like Maple): Wing bolt blocks, landing gear blocks

Balsa: Everything else

There are always exceptions. My 40 size Corsair uses "hard balsa" wing spars. If you list whose plans you have, maybe someone has built the same plane and can offer first-hand info and lessons learned.