DJME80, I agree with micalbrch. I would not on principle 'blacklist' or give bad marks for any producer, as there usually is a price difference between higher and lower quality, and a lower price and quality could be the right choice for the right circumstances.
You are however obviously after the high quality end, and wish good value over lifetime.
Wich brand and exact material and trim solution to select will depend also details on your process (process water, chemical composition, pressures, flow etc) but also availability on the market, and commonly used and recommended in your area.
(Please remember that this site represents products and people from all over the world, so it is not that easy to come out with a particular brand. At the moment we can only make a guess that you want US standard, but it could be JIS or EN or anything else. And why are you so sure you only want to evaluate gate valves?)
By asking possible suppliers for suggestion of brands and types with recommended alternatives for longest possible lifetime (not only cheapest buying price), with argumentation for construction details, and with references to long-term customers and installations you can contact, you ought to get both a qualified range to select from and data to set down on paper a technical/economical evaluation of the different choices.
Good luck!