I've been using the free (and for a time the paid) Canva account. The UI in canva is familiar and easy to navigate. However, the Design Wizard UI and experience is far superior. This is probably the best (and I don't say that lightly) interface that I've ever used. I'm eager to hear about the roadmap. As far as Canva, the features I really wanted was transparent image download and resizing, which for $12.99/mo wasn't worth it. Sumolings will not be disappointed.

PROS:
the templates are crazy good and there's lots of them
the videos/background/stock photos are really quality and not found on others (like pixabay)
image search has like 10-15 filters making finding an icon, image, or whatever much easier.

CONS: finding the right templates, sizes and such could be improved, although I've just started using it and have had no problem finding things based on the common keywords I normally search; the storage might be a downer, but I'm not sure how much storage each design would take (assuming it is 1MB, that 500 designs). I don't imagine I will need that much space nor would I want to resuse many of my designs so I may just download.