The difference is personal preference. DAO would require a diliberate cycling of the trigger each time one wanted the gun to go bang. Less likihood of ND/AD by some peoples assessment. I personally prefer to keep my options as open as I can and prefer DA/SA mostly because I'm not a fn of the "cocked and locked" thing. Open options for me is also streamlining and an extra step to drop the safety just doesn't fit my definition.
Neither one is any better than the other in most regards. It's just a feature. Do you like/want it in the handgun you are choosing? Why do you want it? Are you comfortable using your firearm with a particular action? Some people, for whatever reason, want the heavy 10-ish pound pull for every shot. I practice DA shots when I go to the range as I figure I may not always get an opportunity to cock the hammer before taking my shot. However, I personally like having my follow-up shots sent down range with a 4-ish pound pull.
Personal preference is all. SAO, DAO, SA/DA and all the variants of them. If it's something you like AND want, by all means do it. You have those choices in this country. Have fun with your decision.