Balrogs and Sauron

One thing i believe is that Gandalf could easily have been Saurons equal, but in the "spirit realm" so to speak. When Manwe asked Gandalf to go help middle earth, he was afraid to come, not necessarily because Sauron was so powerful, but because Gandalf could not use his Maia powers in middle earth to rival Sauron. Gandalf was the only one who succeeded and stayed the course, so that must be why Manwe chose him because he could percieve what was to happen somewhat and he knew Olorin was true of heart. Maybe I am rambling, sorry.