Today, Phase One released a beta of their new photo manager and RAW developer application Capture One.
The interface is still the weakest point but they have made a great leap forward if you compare this new version 4 to the previous version 3, which feels like a GTK-application converted to Java and run on Mac OS. (a nightmate)
Straightening an image is done differently to Aperture - in Capture One you mark a line which should be straight using two clicks. In Aperture you rotate and auto-zoom the image until something aligns to a grid. I would prefer a combination of the both techniques.
My conclution is: stick with Aperture a wee bit longer. Capture One is still in beta and I really hope that the Danish folks at PO will shape things up and release us all from the Aperture prison of slowness.