The problem with slow cookers is that the chop a bunch of stuff up, toss them in the slow cooker, and turn it on approach doesn't work all that well. You generally want to brown things etc.--and then you're not gaining that much. But, then, I'm mostly not a huge fan of stews in general.

Absolutely, pretty much anything I could think of doing in a slow cooker would be better off done in a pressure cooker, for about the same time investment from me.

Sous-vide much more specialized, but I find super useful not for saving time, per say, but being more flexible about it. It's great when you are doing other things at the same time as cooking dinner, i.e. - leave the steaks another 30 min while I do this chore? no problem....

Or a crock pot.