Balsa USA, in my experience, has good plans and instructions. The WWI kits are basically a huge Guillows kits.

For me, the major detraction is the amount of soldering required. If you are comfortable with that, you will probably enjoy building a BUSA kit.

Be aware that although similar to a Guillows kit, BUSA kits will be more advanced, New techniques will be required. If you run into difficulties, the RCU community is here to assist you.