Cases serve two purposes. The first is to protect your computer components from the elements. The second is to make a fashion statement. The first is possible to measure. The second is a more taunting task. Things that a geek consider 'really cool' have little impact on a fashion designer. The decision often comes down to which one looks and feels the best. This type of subjective decision is beyound the scope of this article.
A good computer case is an investment. A good computer case will survive several major upgrades. A good computer case will rarely give you cause to curse your case decision. On the other hand, a good computer case will cost more than a cheap case. You have to decide if you need the flexibility of a good case of if you are they type of person who will purchase a new system every few years (where few is less than 5) rather than upgrade. Anyone who buys a computer expecting it to last more than three years will be disapointed in todays changing times. Applications continue to grow to exceed the capability systems that grow to meet the needs of the applications. You really have but three basic choices: buy new systems every few years; allow your hardware to become obsolete or upgrade your system over time. Those of you who are in the first category can stop reading here. You should buy the cheapest case your clone shop sells and throw it away with the computer after a few years. Those of you in the second category need to be a little more careful. I have had the power supplies that come in cheap cases last as long as 5 years and as short as 9 months. I would say the typical life expectency of a cheap power supply is on the order of 2 'no service' years. You can probably get another year out of them with regular cleaning. Cheap fans and cheap power supplies are fine if you are going to dispose of the complete system in a few years. They are the bane of your existence if you hope to keep the system for any period of time. Those of you who plan on keeping your system for five to ten years with appropriate modernization every so often should continue to read this article. Your needs and mine are similar and what I say should apply.
I found the Ars Technica: Case Considerations page after I wrote the first draft of this page. They cover the material almost as good as I wish I could. I suggest you read their material.
The absolute best case if you want the ultimate in expandability and do not mind taking a rediculous amount of space is SuperMicro SC-750A made by Addtronics. This case is HUGE. I selected the SC-750A case for the Wimpy project. I spent hours looked at the dozens of cases at Central Computers before concluding that the SC-750A is absolutely the best case on the market for the "power user". I shocked more than one fellow shopper by sitting and standing on those cases that looked like they could take my weight to get a feel for their sturdyness. I made my selection before I found any of the excelent reviews on the net and came to the same conclusion as all the reviewers. The SuperMicro SC-750A offers adequate drive bays and has sufficient places to mount fans to cool the pieces you accumulate over time. You can read the ARS Technica review of the SuperMicro SC750 case.
Addtronics makes a range of useful cases. See their web page at http://www.wco.com/~addtron/ or http://www.addtronics.com/. The Addtronics 6890A is highly rated. Addtronics are the OEM of the SuperMicro SC-750A case and offer their own version with several modifications. Anyone considering the SC-750A case should also consider the Addtronics 7896A. The Addtronics offers a removable motherboard tray and drive rails. I personally do not like either feature so prefer the SuperMicro. You should make your own decisions. Read the Ars Technica review of the Addtronics 689x cases.