I have many different layers displaying each a class level from low (blue) to high (red). As I have many layers on different parameters, some low classes can appear on top of high classes, which I don't want (i want the highest first).
My workaround was to duplicate all layers and display only the class i need, then order the layers in colour groups (see below), which is a bit annoying to do.
A similar problem i think : Setting rendering order of line layers in QGIS
If it was only one layer, I'd use symbol levels but as I have many layers (and I don't want to merge them), i'm trying to find a way to order symbols on a higher level (like in arcgis). Is there something that has evolved in QGIS that could allow me to manage symbol order between many layers ?