Horses + courses….
I’ve had genuine Thermarests for ~20 years and have had no manufacturing or materials problems – ever. I have a Neo Air and a motley collection of standard, pro and ultralite’s bought over time. All hammered, all good.
I also have a couple of Alpkit ‘wannabees’. They are Fat Airic’s (or whatever the latest fatty mat is called) for car camping. Both failed after ~1 year and replaced under warranty.
If you want light and dependable and have deep(ish) pockets, go Thermarest. If any of those three don’t apply, go for a copy.
BTW, if you’re in the market for a Neo Air, there’s a competitor out now that’s supposed to be very good. Unhelpfully, I can’t recall what it is (Pacific Outdoors?). Google will find it.