Personally, I was never a fan of closed off PC cases. Ones with either a solid steel wall, plastic, or glass for a front panel. I've always been more of an airflow guy myself. The fact that mesh fronted cases are becoming a trend is probably one the best thing to come recently.
For those of you that don't care for tempered glass or RGB, and are cool with a full tower, I'd recommend the Enthoo Pro 2 with the solid side panel. I'm not sure if the P600S has the solid panel option, but if you're one of those psychos that prefer to suffocate your hardware, the P600S does include solid sound dampening front and top panels you can just place over the fabric mesh front and top. Though I'll gladly take the fabric mesh myself.
EDIT: Yeah, the P600S does have a solid side panel for 10 bucks less than the tempered glass ones.