A new social system is better than UBI.
Giving money instead of resources is what powers the economy. Even with a BI system, there will always be impoverished people who can’t satisfy all their needs.
In fact, capitalism requires millions, and even billions of people to have their needs unsatisfiable and be in poverty, no matter what.
True, I would also opt for something like a universal basic needs program rather than a certain guaranteed income. Because a basic need program would be an infrastructure providing cheaper and more abundant needs such as energy, food, transportation and education. Based on localization, strategic_access and automation. That would also open up the path towards an RBE.
Such an infrastructure will also remain. While an UBI can be cancelled and then all benefits stop. Also giving people more money may increase consumption and thus resource usage and pollution. Putting oil on an already out of control fire.