Idfixe wrote:Anyone have an opinion on what makes a good knock box?
Depends on you and your workflow and usage.
For instance, initially I wanted a small knockbox because I was content to empty it more frequently. That quickly became tedious, so I picked up a Cafelat Classic in stainless steel, much bigger than my former. Some can't stand the idea of having a 'wastebin' on their counter, but I enjoy having it to throw an occasional paper towel, loose particles and beans, etc. Also, if I had to wipe away wet grounds from the portafilter, I did that over the box. I had to "aim" with the former smaller box, which made it a little more messy. With the bigger, the site is much cleaner.
Most of the brand names you know are all of high enough quality that you don't need to worry about breaking anything. Look for a removable bar to make emptying and cleaning easier, and available replacement parts.