You will get a wide range of answers on this. But 99.9% of all the folks on this forum are experienced, have built their own systems and know what works. Any major manufacturer will produce a decent midtower case. The differences lay in power supply wattage, number of external and internal drive bays, fans, ventilation options and things like that.
Personally, I'm using the Antech KS-282 midtower case. It has an AMD-approved 300-watt power supply and decent ventilation. Some simple case mods turn it into an excellent air-flowing case. As it comes from the factory, it will do you fine with everything up to an AMD 1000 TBird. Providing you're not overclocking. (That's why I modded my case a little)
As I said, you will get different opinions on this question. Nobody is right and nobody is wrong (on this forum anyway!). Antech, Enlight and others all make great cases. You did the right thing by asking. The folks on this forum helped me build my first home-made (I still haven't figured out a cool name to call it

) system.