Frame geometry influences ride characteristics a lot more than the material.
Tubing diameters and design influence ride characteristics a lot more than the material.
Carbon is the best in terms of allowing producers to make ride characteristics exactly as they plan, but they don't always put the effort to make use of that opportunity, not on cheaper frames that come with bikes under 1000$. The same goes for metal frames in lower price category.
Tyre width influences ride comfort a lot more than frame material, frame geometry and tubing design.
Tyre quality influences ride comfort almost as much as tyre width does. This means a subtle, quality tyre will provide a more comfortable ride than a wider, but poor quality tyre. Of course, wide + high quality is even more comfortable.
Choose a bike that you like best when test riding.