Not sure if anybody will have the courage to try it, but Hazal Turkish yoghurt from Migros (big pots only, blue and white) is excellent and to my non-expert palate is a great alternative to the slightly thin Greek yoghurts here
This user would like to thank Caviarchips for this useful post:
As a greek I would like to add my vote to Hazal, "turkish style" yogurt sold at Migros recently. It's basically the same as Total. A third option is Yogos, the Migros House Brand when that cannot be found. I live too far from the gourmet shops in Zurich to be able to regularly find Total so I often substitute. I have a friend who succesfully substitutes Full fat Quark in his Tzatziki without any loss of quality. I also urge any non greek members here to never buy ready made tzatziki. It is basically a rip off. You just need garlic, yogurt( or quark) and a chopped , grated and wrung out cucumber. A pinch of salt and you are done!
Additionaly, ...greek yogurt does not need to be made of goat or sheep's milk as stated by Captain Greybeard. Of course it would be more authentic or Ur-griechisch, but like stated the straining is the main factor in all middle eastern yogurts. I have tried to strain Swiss supermarket yogurt but the taste was wrong, I suspect a different strain of microbes is used to ferment the milk here. I also used swiss yogurt as a starter for a new batch and the taste was again wrong. I am planning a future experiment with Hazal or Total as a starter with raw swiss cow milk.