We have been staying with eurocamp for years and have also stayed with canvas. Eurocamp & Keycamp are in fact the same company but with separate branding and profiles. IMO I would look at the type/layout of accomodation you want and see which company matches this best. We have 3 DCs and have found that we NEED 3 bedrooms so for us the Eurocamp Premier model is our preferred choice. We are less swung by extra bathrooms or dishwashers, it's space we are after.
We stayed on the Adriatic coast a few years ago (Pra Delle Torri campsite). Unfortunately we hated it and left early. The campsite seemed to be run on military lines with forced siesta time (no playing in the playgrounds). The humidity and the nightly mosquito spray put us off. I dont know if it was typical of the area. We have never been back.
Somewhere which could meet your requirements is Vias Plage (there are a number of campsites there). It is within walking distance of the beach and has a bit of a town with places to eat out etc. We stayed at a campsite called La Carrabasse a couple of times. It has since been taken over by Siblu but when we stayed there it was a really nice campsite.