ruger kp90 is still top notch and probably the most affordable quality da/sa in 45 out there.
i have also messed with the taurus pt 945. this is a compact metal frame da/sa 45 that can be carried hammer down or cocked and locked. The feller that owned this one took old GI 1911 mags and cut a new notch in them and they worked fine in the gun----much cheaper than buying the factory mags plus they would still work in his 1911... The da stroke was a bit heavy. I've thought about this one for ccw.............still might when i get caught up on other projects.
lots of used smith 4506's and their variants out there but that is either a love or hate relationship.
the most accurate da/sa 45 that i know of is probably the CZ 97. it is big......it is heavy....and the da stroke is hard for me to reach with my medium hands,,,,,,,but the sa is sweet and she is plenty accurate. its a dbl stack 45 so large hands help.......