RE: Best 12 ga. shot shell for dove...
The load that patterns best out of you gun/choke combination and is comfortable for you to shoot.It's as simple as that. Don't get caught up in all the promotional hype that the manufactuors put out.
If you are keeping your shots within what is reasonable distance (that's under 45 yards ,preferably 40 & under) just about any 7 1/2 target load would fill the bill.My personal choice would be a 1or 1 1/8 ozsporting clay load. Most of these travel between 1250-1300fps are comfortable to shoot.