That is the $64 question, and for as long as I have been doing the defensive shotgun thing, there has been vigorous debate on this topic. This is how I think about the choices.
If your mission is shot and buck, and especially if the distances are close, like for defensive use inside a house, it is hard to beat a vent rib. The vent rib is economical, simple and fast, and has surely killed more animals and people than all the other systems combined.
If you mission is slugs, like my use in Alaska against grizzly bears, the red dot is the best choice for me. This gives me the greatest possible distance and lighting envelope to reliably place a slug.
Where it gets tricky is mixed use of buck and slugs. Jeff Cooper advocated the ghost ring, Louis Awerbuck and Randy Cain like/liked open rifle style sights. Something I found through experience, is a large ghost ring does not work for about half the population, including me. Ultimately, I believe there is no “right” answer for mixed use. I prefer a red dot because I also shoot a dot on my pistol, and I find the dot allows me better accuracy, regardless of my load. The red dot is more expensive, requires batteries, specialized mounting solutions, and takes user familiarity. Three gunners do great work with simple rifle sights, and ghost ring sights are seldom seen at 3 gun matches. Military and LE seem to gravitate to ghost ring sights, although I am not sure how much of that is an outgrowth if Jeff Cooper’s advocacy, that led Vang, Scattergun and Mossberg doing ghost ring sights.
I can see reasonable people disagreeing on the “best” sighting choice based on their mission, experience, and budget.