Some wisdom to share :
"One man's bag is another man's thrashbag". That is the rule when it comes to selecting a bag.
"My wife has her Prada, LV, Hermes... I have my Billingham, LowePro, Kata...."
"There is a camera bag for every different occasion".
"The time when I stop buying camera bags is when they cremate all the bags I have ever bought in my lifetime with me during my funeral".
That said, go take a nice long walk at all the shops selling camera bags and pick a few that takes your fancy. There will never be one size fits all. (or occasions).