CactiGuide.com

Hello guys, from your experiences which cacti is the most sun hardy(tolerates most sunshine without beimg sunburned) and which one is the opposite, that are most sensitive to sun(those who prefer more shade than sun)
Thanks!

In your area with temperate continental climate I think that most, if not all, desert cacti will withstand full sun all year around without problem. Of course, they'll need to be acclimated slowly to such conditions since most of the cacti purchased from commercial breeders come from greenhouses that are almost always shaded to some degree. Cacti that prefer shade are mostly tropical epiphytic plants belonging to genera Schlumbergera, Hatiora, Epiphyllum, Rhipsalis, Selenicereus, etc.

I agree with Nino _G. If you buy or receive a cactus, it's best to gradually introduce it to full sun. Once 'fully introduced' a cactus can take a lot of sun and heat. There are exceptions, e.g. recently repotted specimens are better kept in bright indirect light for a while. The same goes for cacti treated with an insecticide.
I have found that Echinofossulocactus/Stenocactus can be susceptible to sunburn if not properly introduced. Last summer I also had a slightly sun scorched Gymnocalycium andreae and my Mammilaria polythele seems to get sun stressed easily.
I've never had any sun related issues with Turbinicarpus and I've got a few of those.