They are not the best.
1. A lot of tire shops will do a free fix. That is how they make you think they are the "best."
2. If I had $1 for every time they forgot to put TPMS on a tire, not knowing the difference between all-season and snow tires, and trying to push all-season or all-weather because "it is the same." Also, pushing one certain product. When I was purchasing tires for the Sequoia in April, for summer driving, I went to get Continental TerrainContact H/T. The guy pretty much did not want to listen; he was adamant to sell me Pathfinder "whatever" or nothing. Trying to convince me that Pathfinder is made by Hankook, which is the same as Continental (that was the point I lost patience). I just walked away, went to Costco got Defender's.
3. DOT is all over the place. Unlike Costco which always gets tires few months old (I once got from Costco tires week old) DT wants to push old stuff, then arguing over it etc.
4. I still buy some novelty stuff I want to try, just bcs. Costco does not carry. But if Cstco carries, I don't even think about it.