In fact, I have an imagery entry for zoom 17 of DigitalGlobe Premium, because parts of the imagery are newer than Bing.
digitalglobe is very good, no clouds, you can zoom as much as you like, esri has newer images but you cant zoom much
bing is just the default, it is not what most editors use (it depends on the country actually)
regarding junctions, turn:lanes and lanes:forward tags are made for this exact reason
Is there any update about this issue on mapping?