I had a cheap alloy one from Lidl up until last week; it only lasted 3 years so I'd definitely say go for a quality brand. I went for a powder coated steel one by "Hozelock" (distributed by Coopers, I think) this time. I looked at Brabantia and wasn't that impressed- the arms appeared to be angle sections (sharpish edges?) whereas the one I went for had tubular arms with line mounting points fixed to the top (wouldn't weaken the arms and easier to re-string in time, I reckon). This is the third line I've bought and each time the pole diameter is different, why can't they standardise these things?
Regarding Coopers rotary lines: I have a Coopers Roto-dry "Heavy Duty 150" with 10 year guarantee against rust or corrosion, which covers any parts which fail due the effects of rust or corrosion, not including washing line. This was the heaviest duty, longest guarantee against rust rotary dryer I could find from: B+Q, Atlantic Homecare, 4Home, Homebase or Woodies 17 months ago. It seemed better than the heavy duty Brabantia at the time.
I live in a coastal area and put the line up May 2008.
I have just dug out the guarantee, since it has rusted to pieces. It is in no way rustproof. Rust started appearing after 6 months on the rivets holding any plastic or metal parts together, but was merely cosmetic at that stage. Rust has now gotten under the plastic coating on the main downpole and four main struts across which the line is stretched. The only parts that are not affected are: the line, plastic mouldings and aluminium centre stablising bars. It is utterly unfit for purpose, avoid like the plague. I can no longer close the line as there is too much rust on the main downpole. It is now so bad it will leave rust marks on lighter coloured clothing.
Needless to say I will be referring to their 10 year guarantee against rust or corrosion, but I certainly don't want it "repaired or replaced" as it is complete rubbish.
I'm going to involve Woodies, since a years use of a product which states on the packaging: "heavy duty", "rust resistant", "withstands harsh weather" "10 year guarantee against failure due to rust " is well covered by consumer legislation in the Sale of Goods and Supply of Services Act.