After much time spent researching this topic with great interest, I have found that there are many excellant cases out there. If picking out the best, in my personal opinion there really are two out there that stand out above the rest.
One of which would be the <A HREF="http://neoseeker.com/Hardware/Products/LianLiPC60/index.html" target="_new">Lian-Li PC-60</A>. All-aluminum cases such as this and the Coolermaster ATC-201 are a recent revolution in computer cases. Touting over 3 times the heat conduction of steel acting like a large heatsink and several times lighter are obvious qualities, but not the most important (since it may only decrease your case temps by 1 degree or so and most people don't transport their desktop PC much). The reason behind picking the Lian-Li PC-60 is the great hard drive cooling setup (twin 80mm intake fans right in front of the hard drive), filter over the intake fans to control dust, thumbscrews, good airflow, wonderful craftsmanship, and great looks. It is a bit pricy and some people don't like that it doesn't come with a power supply, but I like that you have the freedom to choose a quality power supply to go with it (I would suggest the Enermax 330W Whisper series). Lian-Li also makes smaller cases such as the PC-30 and a larger PC-70.
The other would be the modified Chenbro Genie by <A HREF="http://www.coolcases.com" target="_new">coolcases.com</A> and resold by <A HREF="http://www.caseetc.com/cgi-bin/caseetc/000287.html" target="_new">CaseEtc.com</A>. Jim Hansan at coolcases.com has a stellar reputation for doing great modifications to already good cases for a very good price. His modded cases usually feature regular screws replaced by thumbscrews, regular PSU replaced by a great PSU, professionally made blowholes, grommet mounted fans to reduce vibrations, and more. The modified Chenro Genie with dual 120mm Panaflo intake fans is considered the best all-around case he makes and is very well designed. You can see coolcases.com's reseller rating <A HREF="http://www.resellerratings.com/vendone.cgi?coolcases.com" target="_new">here</A> and caseetc.com's <A HREF="http://www.resellerratings.com/vendone.cgi?CaseEtc." target="_new">here</A>
Of course these are just my personal recommendations and there are several other great cases out there such as the Addtronics W8500, Supermicro line, Palo Alto line, Antec SX830, Enlight line, PCmods.com, Tornado from 3dcool.com, the Max Cool case from thecardcooler.com, the soon to be <A HREF="http://www.faraday-cases.com" target="_new">Coldforge AA-15</A>, and a couple others I am probably forgetting. The bottom line is you should pick out which is best for you. Good luck.