I've used Ergotron monitor arms before, and those are built well and can carry some weight, they're also hefty chunks of metal. Many artists use it for their giant Wacom Cintiq's 22-32 inch monitors, and those tend to be recommended. I had the white one in this photo (web grab), but I've already returned it due to the unexpected Studio Display release:
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As for an actual stand as opposed to an arm? No idea. That's the main reason to why I forked up money for the tilt height stand. I don't use my main monitors in portrait mode ever, and didn't want to deal with trying to find a high quality well built third party stand.
I've spent hours searching for quality made products, but the market is flooded with cheap stuff and it's just a headache to buy and test out (especially if you're the first to). I just hate dealing with returns, customer service, or calling on warranties and replacements. After awhile I just realized the time I saved by going with what's available even at an extra cost is worth it. I can move forward and focus on actually working.
In short, the Ergotron are pretty decent arms. Stands though, no clue.