Every outdoor product survives its first season. That is not a useful test. The gap between a good buy and a bad one only shows up somewhere around month twenty, and it usually shows up as fading, as a smell, or as a cushion that never quite dries out again.
Here is what separates them.
Rugs: drainage beats everything
An outdoor rug fails in one of two ways. Either the sun bleaches it, or water gets trapped underneath and it goes green and sour against your decking.
Polypropylene handles both problems better than almost anything else at a normal price, because it does not absorb water and it is usually solution-dyed rather than surface-dyed — the colour goes through the fibre instead of sitting on it. Natural fibres like jute look better and behave worse; they belong under a roof, on a covered porch or inside a gazebo, not out in open weather.
Whatever you buy, pick it up occasionally. Even the best rug will kill grass and stain a deck if it sits in the same spot through a wet month. Reversible flat-weave mats are popular partly because they are easy to lift, shake out and drop back.
On sizing: the rule that matters is that the front legs of every seat should land on the rug. A rug that only fills the gap between the sofa and the coffee table makes the whole grouping look like it shrank.
Cushions: the fabric is not the problem, the foam is
Most people evaluate outdoor cushions by the fabric. The fabric is usually fine. What ruins a cushion is the core — a closed-cell or quick-dry foam drains and dries; a standard upholstery foam holds water like a sponge, and once it has been soaked and left, it never fully recovers.
The practical test is simple. If a cushion feels heavy the morning after rain, it is holding water, and it will smell by August. If it feels roughly the same as it did dry, you bought well.
Zippers are worth a look too. A cushion cover you can remove is a cushion you can wash. One that is sewn shut is a cushion you will eventually throw away.
Frames: where the failure actually starts
Powder-coated steel and aluminium both hold up well, and the difference between them is mostly weight — aluminium moves easily, steel stays put in wind. What kills either one is a chip. Once the coating is broken and bare metal is exposed, corrosion starts at that point and works outward under the finish.
Check the fasteners, not the tubes. Manufacturers economise on hardware long before they economise on the visible frame, and a rusted bolt in a joint is a structural problem where a scuffed leg is cosmetic.
Timber is a different bargain: it needs attention, and in exchange it ages instead of degrading. Kiln-dried timber that has been pre-stained arrives stable, but every wood structure eventually wants re-coating. If that sounds like a chore rather than a Saturday, buy metal.
Covers: useful, and frequently misused
A cover keeps rain and UV off. It also traps moisture underneath if you put it on wet furniture and leave it, which does more damage than leaving the furniture bare would have.
Two rules: cover things dry, and use covers with vents. A sealed bag over damp cushions is a greenhouse.
The short version
Buy solution-dyed synthetics for anything in direct sun. Buy quick-dry foam or plan to bring cushions in. Check the hardware, not the finish. And accept that timber is a relationship, not a purchase.