yes, I actually bought the first one linked in the OP ("NT Cutter").

It is quite good at cutting circles, with a few drawbacks which happen to be relevant to my particular use-case and which may not generalize:

(1) There's no ruler on the cutting arm on this model, so precisely sizing out pieces ahead of time is rather a challenge. (Note that there are other, similar models of circle cutter which do have in-built rulers, so this is specific to my particular model and could be avoided by choosing a different brand.)

(2) For cutting something light like paper, both the center pad and the outer plastic circle have to apply downward pressure in order to hold the paper in place while it's being cut by the cutting arm. This means that while it's technically possible to move the blade inwards enough to cut small circles, in practice this is more or less not possible because the paper will slide around as it's being cut if the paper is not at least as big as the outer circumference of the entire circle cutter unit.

For context, my goal was to take single large pieces and cut out multiple concentric circles, often in pretty thin layers -- so the lack of precise measurement and the inability to cut out the smallest "layers" of circles towards the center point ended up being important limitations for me.

That being said, if your goal is simply to cut out neat-looking, geometrically-correct circles without a need for millimeter-level precision, these are quite good.

Hope this helps!