I'm using Designer and its great. One thing holding me back from Photo unfortunately is that when i copy and image into the clipboard and paste it into Photo, it doesn't automatically size the artboard/canvas to the size of the image. Photoshop does this as follows.
When you copy something into the clipboard, you do a cmd-n and Photoshop starts a new tab with the Canvas defaulting to the size of the image in the clipboard. This is really useful. I am copying images and pasting into Photoshop all the time.
In Photo, unfortunately, it doesn't auto detect and set the size. This would be less painful if there was a way to quickly resize the canvas to fit the image, but I don't know how.