The 300 is much more "open" case. Lots of fans, and you can hear the noise pretty easily. If you are overclocking, this is a good thing. If you want silence, not so good. And you can get it new for about $50 anyway.
The P182 is quieter. There are several compartments which help isolate sound and heat. Great for silence/quiet, not so good for overclocking.
Both are very nice cases, but you can get the 300 for $50 new so it's not really a deal. The P182 is (I think) about $100 normally.
Appearance is totally a personal choice...