I've been following the saga of tomatoes à la fausse ancienne for about a year now. Famous old varieties, principally Coeur de Boeuf, Noire de Crimée, Ananas, Green Zebra and Lemon Boy, found themselves fashionable and suddenly commanded high prices. But they weren't amenable to high volume production as required by the grands surfaces. Therefore fast and furious research went into the production of look-alikes. These can often be detected by the regularity of shape, size and ripeness of a display of (hothouse) fruit. The real ones, grown slowly out of doors, are knobbly and lumpy, often split and liable to green patches from sun scorch. There was a wave of protest led by certain chefs, incensed by the deceptive labelling of anonymous hothouse tomatoes under heritage names.
Of the 26 varieties I've grown this year, 18 are personal favourites and 8 are new. Favourites come and go but the five heritage varieties above have been on my list for years. Among the cherry tomatoes: Sungold and Nectar plus one of the new ones, Cookie.
To name an absolute favourite is like asking what is your favourite child. If you can't grow your own, find a local producers' stall at a market, or visit a vide grenier in tomato season. They may well only have one heap of tomatoes for sale, and the stallholder may not be able to tell you what variety they are, because he or she saves the seeds from one year to the next. I can virtually guarantee these will be good.
That said, I saw a handsome display of Noire de Crimée at Terre y Fruits in Descartes today. If those were fausse someone has done a good job.