My personal favorites are Geeek A10 & Project Jolokia.
edit: I was mislead by the title and didn't check your GPU preference. But that second slot can always be re-purposed for better cooling or storage in your case.
Is there really enough space for a FlexATX PSU anywhere?
From the pictures of L1/L2 builds, they hardly fit even HD-Plex 250W and L3 is almost same size.