Which of the nebular, tidal , planetisimal, big bang and condensation theories do you find most believable?
I think you’re confusing a bunch of theories here that don’t contradict each other. Nebular, tidal, planetesimal I’ve all heard in terms of planet formation, and while we’re certain planets and stars form from a nebula, tidal/eddy vs. planetesimal is still up for debate – there’s evidence on both sides. Big bang is widely accepted and not related.