Perhaps no other name is as respected in the PC case business as Antec. They've been around for ages - the first PC I built, a 500Mhz AMD-based gaming computer, was built inside of an Antec case - and during their long existence they've consistently built good PC cases. Unfortunately, these cases were often over the $100 dollar mark, putting them outside the price range of buyers on a budget, and this was particularly true of cases like the famous Antec 900.
Not anymore. Some time ago, Antec announced the 300, a case built on the same core philosophy of their more expensive gaming-oriented cases, but given a far lower price, an exterior and feature-set that makes it perfectly suitable for nearly any task. The metalwork of the 300 is not quite as well finished as what can be seen in their more expensive cases, but for a budget case it is very good, and the plastic front feels solid enough to take a glancing blow. Inside of the case, the high build quality continues, with few sharp edges.
Being a basic case, the Antec 300 is missing the features of its more expensive siblings. More relevant to this list, it is missing some options found on some other budget cases. It does not have a tool-less drive mounting system, it has fewer fan mounts than the Centurion, and it has one less front port than the Centurion. It also doesn't have the features of the Smilodon - no removable motherboard trays to be found here.
But what makes the Antec 300 a winner is that many of those features are not needed in a budget case. No reasonable user will put a fan in all of the locations available on the Centurion, and as a result the Antec has a cooling solution which is simpler but every bit as effective. Also, budget users are very unlikely to use all of the 5.25" bays on the Centurion, and the Antec 300 offers 2 more 3.5" bays (for a total of six), which are more likely to be of use. And while the Antec 300 features no LED lighting like the Smilodon, it doesn't need it. The Antec 300 looks elegant and sturdy, which means the case looks at home in nearly any environment. The Antec 300 is inexpensive, too, costing $59.99 (as of 12/20/08), just like the Centurion.
Granted, those users who are likely to be working inside their PC often will clearly want to buy a Smilodon, and those who want to make use of a ton of fans or who need a great deal of 5.25" bays will want a Centurion. But for everyone else, the Antec 300 is the best bet.