I bought some £7.99
Decathlon Shorts used about 2 years and recently got some
Altura bibs circa £ 40? used about 4 months. I also bought some padded shorts of an unkown brand for £15.00 and that was a total false economy as they were binned after no time. Here is my comparison:
Stitching - Declathlon has no holes or problems with stitiching the altura has a small hole right at the very top of the short where the stitching has come apart
Decathlon Pad is thinner than the Altura however that is after two years at the time the pad didn't feel inadequate but if I compared new with new I bet it would.
Decathlon material is thinner than the Altura material
I would probably not buy either again as I have some Mavic Longs and was very impressed but if i had to choose between the two I would probably opt for the Altura. Having said that if you don't want to spend too much but don't want crap either then you will not go far wrong with decathlon. Decathlon also do a range of mid and higher end/pricier stuff (higher end pricier stuff oin the decathlon not assos sense) and I did buy one of their one road so many ways tops the quality was really good but it made me looked really fat so I didn't wear it much. I have now lost some weight and it no longer fits me.
I also rode one of their high end bikes 2.5k carbon jobbies with Sram red one hell of a bike for the money