Qiyana being the strongest elemental mage in Ixtal feels pretty lackluster if you ask me. Her In-Game representation of her elemental skills are just so pitiful, aside from her Q and W (which isn't technically an elemental skill itself) her only real element inspired skill is her ultimate which is just a gust of wind followed by a boom of rocks.
She could have (and should have) been a character who is the master of the elements and can utilise each of them with never before seen proficiency, someone who is highly capable of devastating attacks, creating earthquakes, tsunamis, volcanos, tornados with her magic. It wasn't the case obviously.
In her current state she is definitely outshined by other element users not just a bit but greatly. These are just a few examples of the top of my head: Yasuo, Janna, Nami, Brand, Annie, Taliyah and if we consider lightning and frost as elements Kennen, Anivia, Lissandra and even Volibear can join them.