Before my printer died I have found that no software does the supports I need very well and especially not with PLA. So, I manually add them and the supports just pop right out. Slic3r gets it almost right but they need to add an option to tell it how far away from objects to print them. I have found 0.2mm-0.4mm horizontally (depends on your layer height) and 1mm vertically to be optimal. Can do 0.8mm with a smaller nozzle (mine is 0.35mm) but 1mm works too well.