The HP OfficeJet 7740 Wide Format AIO does an excellent job. For the combat price of a good 200 francs, you can grab it here. However, bear in mind the large dimensions of the device.

If you work a lot with the A3 format and need a multifunction printer that is uncompromising in this respect, the Brother MFC-J6930DW is a good choice: It offers flexible paper handling and prints comparatively cheaply. If not only graphics and text, but also good photo prints are required, the Epson Workforce WF-7620DTWF is more recommended...