My USAF supplied Magnum combat boots are just great!
Seriously, they are comfortable and definitely designed for people on their feet all the time. Maybe I'm just used to them after several years of having to wear them though. The best thing you can do is get rubber mats to put in front of equipment you have to stand over a lot, and most of all take time to sit occasionally! Nothing beats a good shop stool, from tall ones at the bench to the short rollers when working low. Taking the load off for five minutes out of every hour or two helps more than any shoe.