I work in luxury clothing production. This sort of information isn't typically available to the public, but it exists. In terms of fabric, every textile we use has a technical data sheet we get from the mill that weaves it. That sheet has a ton of things on it including weight, colour fastness, warp and weft shrinkage etc etc. Construction details are in the tech pack for every garment, these are put together by the brand's product development/production team, people like me. It's a blueprint for how we want the factory to make the garment - seam types, fusing, linings etc. One of these documents is called the BOM or Bill of Materials and contains every little thing that goes into the garment right down to thread type. Some brands (good ones) have very detailed tech packs and BOMs and carefully control their garment quality, others are very basic and allow the factory to make a lot of decisions. Again, these documents are proprietary work product and not available to the consumer.

You can educate yourself on things like seam types and construction methods by looking at books on sewing and tailoring. Most of these are for home sewists and don't use industrial methods but will still give you some guidance on how to identify higher quality finishings.

A word on price. High price does not always indicate high quality but a low price always indicates either low quality materials/construction, or inhumane labour practices. It is simply not possible to make a tshirt for $5 with good materials and construction and pay people fairly to make it. We audit every supplier we work with and I visit our factories multiple times a year. They are clean, safe, decent places to work. We produce our own fabrics and I've been to the Italian mill that makes it. One of their print machines is literally the size of a small flat and cost €2 million. Quality costs money.

I work in clothing production. There are literally tests for every kind of durability you can imagine, made to simulate real-world wear and tear. You send in sample garments from bulk production to a company that specializes in these tests and they put them on a machine that replicates say, two pieces of fabric rubbing against each other 1000 times, or pulling on a button until it pops off. Only some of these tests are legally required (the button pulling for kidswear, for example) but they are available to any brand that wants to know how durable their clothes are.

I would choose Patagonia out of those two, but here are some other brands to check out:

Paramo is very good quality and an ethical manufacturer. No lifetime guarantee, but they have a guarantee against defects and also a repair/alteration service.

Rab is also superb quality, check out their Latok or Resolution insulated jackets which would be in your price range on sale. They have the same sort guarantee and repair services as Paramo, and they also have a professional wash service - a lot of waterproof jackets are ruined by incorrect laundering. I have a lightweight Rab jacket (women's Kinetic) and I love it, super breathable but the rain just off it.

I absolutely love my Ikea HOVAG mattress.

It has a 10-year guarantee which is certainly not for life, but at 179 GBP, I could buy several of them for the price of one of these other mattress brands.