Years ago I discovered Nicholson patternmakers' rasps. They were a quantum leap above the other rasps in their range, which were a cut or two above the general chain hardware store things.
Then I discovered hand-stitched rasps! They are another cut above the "Patternmakers" and even better still, can be had in a wide range of tooth sizes - that is a major factor in their favour, imo. I have Liogiers, and have only used a single Auriou, but I'd guess they are very similar if not identical for quality & functionality, which the Liogiers have in spades.
I use rasps a lot, they are the bees' knees for complex shaping of our hard, gnarly woods. The Liogiers all are superb tools, certainly not cheap, but seem to last a lot longer than cheaper rasps, so not quite as expensive as they first seem. The law of diminishing returns applies very much in this instance, you pay a lot for the increment of improvement vs cheaper rasps, so you have to weigh your needs & desires and balance those against your budget. I have a single Italian hand-stitched rasp which cost a lot less than the Liogier equivalent. It's not quite up to the quality of the Liogiers (a few rough & uneven teeth along the edges that can catch on parts of the job I don't want marked!), but if you are an occasional rasper, might represent better bang for your buck....
Cheers,
Ian