Most recently I came from an Air 240 to Define Nano S.
Air 240
-So-so build quality, thin plastic panels.
-Illogical design oversight of EPS cable routing hole getting blocked by 3.5" drive rack. Only way is to use a further grommet or remove 3.5" rack (oversight also pointed out by linus tech tips)
-Back chamber too spacious, front chamber PCIe clearance is bad (clears up to 130mm GPU width inclusive of PCIe connector)
My overall rating is 3.5/5. Corsair products still fits my conjecture that they're somewhat premium priced, but the amount of attention that goes into the nitty gritty details are sometimes overlooked.
Nano S
-Good build quality (even for the plastic parts) at a lower price tag
-More modularity and easier to clean
-Fine details are well thought out, efficient space use, no major gripe.
My rating is 4.5/5, would be nice if it has a PSU shroud and back chamber is 1/2 to 1CM wider. There's also define mini c for mATX case. Might not be a love at first sight, but you'll probably learn to appreciate it over time.