it depends on how hard the soil is in your area. The marsh for example is heavier than a sandy soil. Furthermore, the Favorit 1 and 2 are very light tractors in terms of their strength. I can't recommend a certain make or model, but I think a small 12-14 inch 3 furrow plough is a good compromise. In my opinion, a 2 furrow plough, even it is bigger than 14 inch, looks like a toy on the back of a Favorit.
P.S.: Excuse my english.