Best arm options for 27" monitor

Hey. I’m looking to get a desk mount monitor arm for my 27" iMac.

There was some discussion of this a year or two ago on the forums, but I’m interested in hearing any opinions/experiences/suggestions for an arm that would provide convenient and safe positioning for the weight (20.5 lbs.) and width of my new machine.

Thanks in advance for any suggestions guys.

Watch out dude, the 27" iMac is 30.5lbs, not 20.5lbs whole other class of stands.
As for choosing the specific one u can check out this Computer monitor stand guide, plenty of good options here