[Engel]

I've checked other because I haven't used any listed but here's the ones I have used that have been really quiet:
P@h 7" wheel (they did have a set colour for each size, it was the blue, but was bought years ago so may have changed).
Trixie 11" plastic wheel. Had 3 of these running at once at one point and all you could hear were little feet.
Speedy hog 16" wide track. Got for my rats and it's great. I've added this one because they did make smaller sizes for hamsters (don't know if they still do)