+2 on the Middle Atlantic lines already mentioned, I have used both for wall mounts for years. For floor-standing racks, I use the Middle Atlantic ERK series. Most of their racks come with a back door (if applicable), but no front door, so make sure you order one separately. You can choose from solid metal front, perforated, or plexi. The fan kit option is nice if you have a solid front door and need to keep internal temperatures down.