I am building a few business machines for a friend and I am looking for cases that are reasonably small, simple, and ultimately inexpensive. I like the corsair carbide 88R but it has a side window and I would rather not have that.
Depends on if you want Mini Itx, Micro ATX, or ATX. I usually like the understated nature of Fractal cases, and I think that it applies well for the business place. But it will also depend on the type of business that it is. Is their office very official, more laid back, very modern? You should look to match the overall aesthetic of the office. But yeah, my first thought is a Fractal Design Core something.
Fractal Define Mini, Fractal Core 1100, Cooler Master N200, and Cooler Master MasterBox Lite 3 look like they can fit into a business environment. My suggestion is to not go too cheap on the case since you want the machine feel high quality instead of flimsy.
Why? It's an office PC... Probably Pentium using it's integrated gpu... For home gaming whatever else pc I would have already said "core series is crap", but the top mounted psu and side mounted hard drives and bad airflow don't play any role here. Seriously, it's fine... I wouldn't even say S220 from NZXT... I would say S210... And even that is large, if the system is matx...
For a business machine I would buy a case with good sound isolation because the last thing you want is hearing pretty clearly the PC running. So I guess a Fractal case can work pretty well. Also the Cooler Master Silencio is a good choice.