Omnimount for price, Chief Manufacturing for engineering. You never did mention the required extension for the articulating arm.

Example: An Omnimount bracket with 26.5" of reach needs 6.8" of space behind the panel, the Chief Manufacturing bracket with a 37" reach only needs 3" of space behind the panel.

The Chief PDR and PNR brackets are both good for 200 lbs. I've never been worried about hanging anything off a Chief bracket.

[Link: chiefmfg.com]