I have 6 HTPC/PCs so I am a little bit tight on the budget.
I am quite happy with the Cooler Master Cavalier 2, cheap price but nice built quality especially the front panel, decent air flow...cons: proprietary psu and the back 6cm dual exhaust fans are noisy.
I also have a black Sliverstone LC11...beautiful case with super innovation (whole thing is inverted), good cooling, quiet. cons:those specific riser configuration is a major PITA, severely limits the mono choices...I have to stick with a mobo that fits the configuration which I am not too happy with (Asus M2A-VM HDMI)...I am not using the HDMI module either because I would need to buy the PCI-E riser (>$50!!), also proprietary psu as well and it is a little noisier than i like when it is warm.
The third HTPC/Desktop case is an AOpen H340, actually pretty good quality, suitable for a cool running system like a Sempron or Athlon64, very portable and light. It uses proprietary psu (only 200w) and low profile cards though. If this one dies, I would immediately replace it with the Antec Minuet becaue I love low profile cases.
All the rest are just boring towers :~)