... and in what size class/engine configuration?
I personally found that in general the 4-cylinder CUTs are notably smoother than 3-cylinder units (even though technically a 'straight three' can be inheriently balanced where a four is not).
That difference was still true (IMO) within the Deere line - I thought the 4 cylinder large-frame units were smoother than the 3 cylinder mid-sizes. To me, neither are butter-smooth, neither were obnoxious. I never dragged along my db meter, but I didn't subjectively notice much difference between noise levels from the seat on different brands.
And in the seat my 4710 seems fairly loud to me (when without hearing protection) but several people (as bystanders) have commented how suprisingly quiet it seems, and claim they can't even hear it running when I get out in the fields 1/4 mile off. OTOH, a neighbor who runs a Christmas tree farm a few hill's over has an older and fairly large Kubota CUT (didn't get a model number) and it can be clearly heard running (when just driving along, not brush-hogging or anything) 1/2 mile away.
Bottom line - I didn't notice enough difference in noise/vibration differences within comparible CUT classes to worry about. Other aspects / features of the tractors were far more significant.