These cases are both ugly. The Level 10 should have been done with different colors on each little part (like each drive bay a different color, the power supply area a different color), making it some kind of trendy flower child case. They could make it in vibrant colors, and another in pastels. People like colors. Making it different than the typical rectangle helps, but they should have spent more time making it pretty, rather than just different. Colors would help a lot, paying more attention to each shape and making subtle modifications could as well. Efficiency? Who cares, it's not like you're going to drive this thing through wind at 100 mph. A little wasted space isn't going to have a materially negative effect on it, and in fact they waste a lot of material with the design as is, so cost isn't a big consideration already.
The other is just a block. Who cares? No one is impressed with oversized cases, so I don't know where that comes in. If you see clients, you go with a laptop. You really are going to impress them lugging over a huge desktop. You'd look like an ass that couldn't afford a laptop, or strangely refused to buy.
I'd pay more for the case than any other part. The reason is simple, you'll have it forever. It won't wear out, and it's not very likely to become obsolete anytime soon. ATX has been around for a really long time.