IQrouter is plug and play after having payed upfront for the benefit. Some of its technology is protected by patents (one of which I filed third party observations against). It is likely not very configurable. You have a small choice of hardware. It is backed by individuals who want to make money.
OpenWrt is free, highly configurable and you have a huge choice of hardware. It is not plug and play. It is backed by enthusiasts working on things in their spare time.
I am the maintainer of cake-autorate, which provides the adaptive bandwidth aspect of cake. No head-to-head comparison with IQrouter has been made so I can't accurately report on how the performance of the adaptive bandwidth aspect compares. My arrogant guess is that cake-autorate outperforms whatever has been implemented in IQrouter, but I'd be happy to be proven wrong because that would motivate further work on cake-autorate to beat IQrouter.
You can read through user reviews here:
https://www.amazon.com/IQrouter-Self-Optimizing-Router-Improved-Quality/product-reviews/B07Y8TQ5C6