Unlike image generators that limit image outcomes to fixed sizes 1:2, 2:1 etc., Sivi allows me to create visuals for my campaigns in virtually any size I want. I got multiple creatives for my website banner in 2 min 34 seconds. The notion-like editor where I added the text and images has many features. Some tutorials here would help.
Editing the creatives look similar to Canva. Gradient fill, image fill, etc. are useful features.