Not to pontificate, but the 'fItures' you mentioned (correctly spelled FEATURES) of having a power supply included with a case is dubious at best. There are some exceptions - such as the Antecs - but even their bundled cases and power supplies do not come with their best power supplies.
Antec's bundled power supplies are generally better than most generics - and will work well for most applications. The preferred solution is to purchase a quality case and a quality power supply to accommodate your specific needs.
Cheers.