I personally wish for Moondragon and Phyla vell to return somehow( i know they are dead or at least phyla vell is) i would also like to see Mantis return.
As for new members. I think Xavin( previously seen in the runaways) would be an intresting member for a little bit. I think Xavin would find them after maybe escaping the Majesdanian's. She would be trying to get back to earth and Karolina, but ends up teaming up with the GotG for awhile. Eventually making her way back to earth.
What characters would you like to see join the Guardians Of the Galaxy?