I tested all of the sauna woods and I found poplar to be the best, it doesn't smell and it's also self cleaning.

Hemlock is self cleaning also but it has a mild smell to it. My sauna that I'm ordering will use Canadian Hemlock because I'm getting something cheaper ($2700) with good quality heaters. If I went with poplar it would cost me $8400.

Cedar is not advised since it off gases and some people with lung issues or allergies have problems. Maybe it is ok for most people, but it's not ok for most people on Curezone.