Which instrument is better for folk guitar ensemble?

This is very simple. You can have many choices. First of all, folk guitar can be combined with folk guitar. Folk guitar can also be combined with electric guitar. Everything can be done. Other instruments can be combined with saxophone, but you can only connect speakers. Because saxophone is loud, it can be combined with piano. I haven't tried the violin, so it should be ok. Now it's popular to cooperate with symphony orchestras, so let it be. No problem. Come on, I hope.