My response may be a bit late, but both cultivars are very useful in the proper setting. C. 'Phasion' aka C. 'Tropicanna' is likely more widely grown and the variegated foliage might be considered more interesting than the red blooming C. 'Australia'. The latter will typically grow taller but is less vigorous but more floriferous.
Finding healthy plants is important so be aware of that issue.

Kent

Also important to note is that C.Tropicanna had a second hybrid introduction in North America. It is available with either an orange bloom (original) or the later hybrid with more pinkish bloom colour.

I have just found a relatively new variant of Phasion or Tropicanna and picked it up. It is called Tropicanna Black.
For more information and photos please refer to:
www.tesselaar.com

They are branding a Tropicanna Gold also, which unless the
hybridization PPAF is different I would think is aka. Pretoria aka. Bengal Tiger. Any thoughts from forum members?

For those who may be somewhat confused or misled concerning the Tesselaar canna releases:
There are at present 3 canna cultivars that have been in the North American market for a few years.
C. Tropicanna sometimes listed as C. Phasion
C. Tropicanna Gold
C. Tropicanna Black
C. Pretoria aka C. Bengal Tiger "is not" the same cultivar as C. Tropicanna Gold. I have posted and commented on this forum in the past and posted photos showing the distinct differences. If you wish to revisit those discussions do a search for Tropicanna Gold in the search box at the bottom of the page. Please keep in mind that I am not saying that unwitting sellers have not sold the more available C. Pretoria as a substitute for C. Tropicanna Gold.

Regards,
Kent

Hi Kent this is all good information.
I will review C. Pretoria and C.Phasion Gold.
I hope this will shed some light on the subtle differences.
Thx.