I discovered this brand years ago when I found them reboxed at a bike shop. I have been purchasing Kenda tubes ever since. They are extremely consistent on the amount of air they lose over time. They have never let me down.
Over the past 2-3 years, I've gone through close to 30 of these tubes. Mainly because I carry spares and don't need them myself but give them to others on the roadside. I use the 60mm presta valve tubes paired with 700x23 Specialized All-Condition Armadillo Elite tires and the last 10 times I've used tubes is because I got a new wheelset. I can't remember when my last flat was. I do always pump up to 125psi before I leave my apartment. There's no reason to spend $6-12 per tube for a name brand. Besides, Kenda is itself a brand name. I won't buy other tubes.