Several -
This is my first RTT and I haven't even laid down in a Tepui yet. I did check out the Yakima at the store.
First off, this is Yakima's first product. Not to say they don't build quality racks, but I was dubious they have tested their new tents as much as Tepui has been tested and tweaked, including in wind, storms, rain chambers, etc.
Secondly, the price is the same. So that didn't seem to make a difference, so I was leaning toward the more robust version. I did like the light weight of the Yakima tent, but at the same price if I can get twice the durability it seemed like a good decision.
Thirdly, I called Tepui and they answered all my questions, a real person picked up the phone without an operator or push button menu, and apparently Tepui is one of the few employing an actual QC person at the factory in China where GoFSR, Tepui, CVT, Gordigear, etc all manufacture the same tents.
Lastly, when I was laying down in the Yakima tent in the store, I could see dozens of pinholes in the stitching of the tent where the material had been pulled too tightly or thread too thin, but there were a lot of places for water intrusion in the tent body itself. The Tepui's are all taped / seam sealed and from what I can tell, on the tent body as well as the rain fly. I think the Yakima will be a great tent, especially for only occasional use which is the category I fall into, but at the same price point I just decided to go with the known quantity and the company with a few years experience and quality control building them.
I'm not sure you can go wrong with any of the half a dozen or so that are listed above and manufactured in the same place. I might have been swayed if Yakima had done anything to differentiate their design, but to me it just appeared to be the standard construction / design / format all be it with lighter weight materials.
Hope that helps some! In either case, I can't wait to get mine and get it out to the woods!