Not to forget that those who use "one of the better" sound wishy-washy.

No, Brian W is wrong. I'll use an example of better and best, which can be applied equally to more and most.

In a set group based on criteria there can be "the best thing." In a larger set "the best thing" of smaller sets can form a new set "the best things"(or "those that fits best thing criteria of all finite sets"). This set is finite, and "one of the best things" makes sense.

In a set group based on criteria there can be many subsets of "better things"(i.e. group of things better than non-zero finite members) specifically sets of (n-1) sizes, the largest being the set of (n-1) size including the least. IOW, "one of the better things" means "everything except the least one."

"One of the (comparative)" is always wrong. It's always "one of the (superlative)."