I have an F-150 in my driveway with an automatic transmission, and in my shed, I have an F-350 with a manual tranny. If I'm driving around town, where I need to shift a lot and would prefer the better mileage, the automatic F-150 has the advantage. When I need to pull a three axle stock trailer loaded with bulls, having the extra power and direct control in the manual F-350 is the advantage.
Maybe the metaphor is too thick.
I have DA's and SA's both, in big bores and small bores, rimfires and super magnums. Most of the time, I pick a DA/SA, and only fire it SA, simply because I like the opportunity to load and unload more simply and quickly. There were years, however, where I preferred single actions.
I'm also a huge fan of fixed sight revolvers, in DA or SA, but decidedly moreso for SA fixies. There's a sleek, elegant sex appeal for a fixed sight single action revolver that's simply unmatched by DA revolvers, or adjustable sight revolvers.
Price is something I've come to not consider most of the time for my firearms selections, but for many, it's a driving factor. Single actions are less expensive than their equivalent double action counterparts.
I suppose one could point out that the DA/SA trigger is generally inferior to that of a SA, for feel, overtravel, and pull weight, as well as trigger reach when fired SA. Due to the long trigger travel, DA's are generally fired with a different part of the finger, which puts the trigger further rearward into your "fist" rather than out in front in a normal position as an SA revolver trigger (normal as compared to rifles, shotguns, and other non-DA firearms). SA's tend to have a longer lock time than equivalent DA's, which makes them less forgiving, but it also allows trigger geometries that allow lower total pull weights with reliable resets. DA's also tend to have more over-travel in the trigger as well. Is it really enough to make one largely superior to the other? Eh, not really, unless you really need a sub-1lb trigger.
