I have Michael Lindsey, Athens, and Venus. I planted them about 5 years ago, I think.
My favorite for scent is Athens. It's a sweet, strong apple scent (maybe sweet, green apple?) that I can detect easily from six feet away. It took a few years to really get to blooming a lot but it was well-worth the wait. It's a little smaller than the other two cultivars but it has a great form. Also, it seems to take drought and alkaline soil just a little better.
We had three Michael Lindsey but this year we took one of them out. It was a healthy, beautiful plant but I wanted something else in that spot. It was a shame that I didn't have anyone to give it to. This is the only cultivar of Calycanthus that has suckered for us so far (I have at least one out there now with suckers). They also have seed pods. The scent is like fermented apple cider and seems to vary by temperature/time of day/year/whatever. It's not a real strong scent like Athens but sometimes I can smell it walking by the bush. I think that Michael is the first one to bloom in the spring.
Venus has the largest flowers and the lightest scent. Most times I can't detect a scent but when I can, it's more of a fruity (pineapple?) scent. I'm not thrilled with the form of this plant. It's too horizontal for me. Maybe that's because I have it planted in more shade than the others. Venus will probably visit the plant heaven in the sky next year. The flowers are pretty when they first open but it just doesn't fit the spot I need to fill.
I have read that even though Calycanthus is fragrant, not all individual plants may be fragrant (even if they are the same cultivar). The fragrance can vary a lot from plant to plant. But I have no way of knowing that from experience. From experience, I can say that they do get more fragrant as they mature. The first year or two with Athens, I thought "Meh". Then the next year, it was "Wow, I love this plant!". It just keeps getting better and better (and more fragrant).
