Depends on how you define "best" .
Bang for the buck, I'd say it's hard to go wrong with the Smittybilt. Their Overlander XL is nearly half the price of comparatively sized Tepui and CVT options (at least it is in Canada) at just over $1500 for a large tent. Combine that with the "no questions asked" extended warranty from a place like 4 wheel parts and you've got a decent tent for the price. But if you are at all brand conscious this might not be for you as Smittybuilt has a reputation which is only sometimes deserved, but often negative.
I have no complaints about my previous Tepui. We'd still be using it but wanted a bit more room. It wasn't without its issues but it was an early one and they've been making improvements ever since. The customer service from Tepui was top notch even across the border. CVT is comparably good, and I give huge props to the boys in Bend and Santa Cruz for their way they engage the community. Fundamentally though their tents are not that different in terms of the specs of the Smittybilt. Same quality of fabric, zippers, etc. One can argue that the quality control of the CVTs and the Tepui's is better but there are smitty dealers all over North America so the risk of getting a lemon from Smitty is mitigated. My own Tepui was not that different in build quality to the Smittybuilt tent I checked out, but remember mine was 6 years old and Tepui have been making improvements each and every year.
In this family of tent you've got the $2300 dollar plus tents going on for a comparable size to the Overlander XL. There's no brand hesitancy and there's something to be said for supporting those that support the community.
ARB is where you see an appreciable difference in build quality in my opinion with better zips and fabrics. The ARB are comparable in build (and price) to the ruggedized versions of the cvt and Tepui line based in what I've seen.
The next level is to the crazy expensive EeziAwn and their kind. If you are living in it everyday and cannot afford a broken zip or tiny leak to your accommodations after a few hundred nights, and can by virtue of opening it up every day for years ensure there's no mold and such, then these are the ticket and will last a lifetime. But for the hobbyist overlander who gets out in the occasional weekend and may be stowing the tent wet or whatever, you are probably better served by one of the other options. Let's face it, stuff happens from flying campfire emblems to plain old post - trip laziness causing mold and I'd feel better about writing off a $2k tent instead of a $5k one! I am much more likely to tackle a home repair of a cheap tent than worry about wrecking a pricey one.
Expedition Portal has a good write up that is I think reasonably fair (with the exception of advising caution about Smittybilt because of folks detracting them as the walmart brand for off roading).
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