Well in the UK the hard box cleaners were superior. There were no two ways about that. Hard bag (hard case) cleaners appeared more modern, they looked sleek, and were usually far easier to fit paper bags to than the soft bag cleaners on sale at the same time, many of which used a rubber ring to attach the paper bag to the dust tube. Also, they were often easier to clean out, particularly if a dust bag had burst, as all that was usually needed was a damp cloth, unlike on a soft bag which would retain the filth in the weave of the outer bag. Furthermore, the physical nature of the hard bag cleaner gave way to having cord winders, air fresheners, electronic power controls, carrying handles, bag full indicators, and later still on board tools fitted into them. This was mostly, though not always, impossible on a soft bag cleaner, and of those soft bag machines which packed such a feature or two, many had a hard plastic compartment to it in addition to a soft bag.
Although soft outer bags were seen as old fashioned and dated by a good deal of people, manufacturers did recognise quite strongly that they were still in demand amongst several consumers, typically the older consumer who liked and identified easily with the traditional soft bag, and those who required a physically lighter cleaner, and, because the price of a soft bag cleaner was usually lower, it also appealed to budget consumers too. So much so that during the early 1980's, Electrolux brought out it's first ever soft bag upright cleaner, bearing in mind that they'd been producing hard bag cleaners for about 15 years already.
When the Hoover Turbopower cleaners went on sale in the early 1980's, there were two soft bag cleaners included in the range and furthermore were still on sale under the name Junior almost 20 years later. In terms of cleaning performance, the soft bag Turbopower machines did not differ from the hard bag versions, it was only features and styling which put them into their own category, ticking all three of the boxes I mentioned earlier.