I have never used Renogy but I think the major factor is their controller may have or might have had some issues. I don't think they make a 200 watt portable but maybe.
I met John Zamp at our facility in 2009 or 2010 I forget exactly when he was just getting started. Absolute amazingly driven man and he was determined to be the best. Zamp is producing their products in the USA now and that might be part of the price difference but honestly I didn't compare. I just know good stuff when I see it. For example, he dumped the Anderson style connectors and made a better one. All aluminum framing is resourced locally, etc. Panels are also made here now. Great products and great company all around and they answer the phone too!
Randy...Converters, Inverters, Trimetric, Surge Protectors, Zamp, Smartplug, AGM Batts