It's pretty tough to pour a large concrete slab as an exterior surface in extreme climates so that it will not crack. For an exterior patio I do not find a poured slab of concrete( even if it's stained) to be an inviting surface. If your contractor is talking about stamped pattern concrete I would warn you that those surfaces can be extremely slippery with a little bit of snow on them( even with grit added as an anti slip). My inlaws had stamped/ stained concrete done for their front entry steps and it is a nightmare with snow on it.
I would say the cobbles you're considering are a much more inviting and practical choice.

Our concrete subcontractor would say that it is not "if" concrete will crack, but when. The concrete is going to crack - it's just a matter of time. I would go for the pavers, we love ours.

We had stained, patterned concrete around our pool and patio but had to change to pavers after several years because of cracks and faded look. Pavers will save money in the long run. And look much better.