I believe 90% of those bench grinders are all the same design. I’ve seen the same identical machine, with identical castings, from several sources. They are all kinda crappy, but good enough for homeowner use, in fact I use the same.
More importantly, decide how you want to manage your sharpening.
I am a big fan of saving daylight for cutting, and doing my sharpening in the evening, so these bench grinders work great for me. I keep a stock of 4 - 6 chains for each of my saws, and just swap them as needed, often more than once in a full day of cutting. When my stock of spare chains gets low, I plan an evening or two during the week to do some sharpening on one of these bench grinders, in a heated shop with the TV or radio playing. It’s my preferred way of managing this chore.
Others prefer hand sharpening, and doing it all in the field, on the saw. Most who go this route just plan to go over the chain with a hand file between every tank of gas, or every second tank at most. These guys are fastidious about their chains, but they must have more spare daylight hours to waste than I can afford, there’s no way I’m going to sharpen a chain during my few precious hours spared for cutting. These guys might only have one spare chain per saw, which they will need if they hit a rock or a nail, there’s no way you’re bringing a chain back to life with a hand file in the woods after rocking it.
Then there are all the gadgets that are some compromise between these two extremes. Things that clamp on to your bar, and sometimes use a Dremel type tool to do the sharpening. I’ve never seen a pro cutter use anything like this, so I relegate them to “hobbyist gimmicks”. But then there are those who use and love these tools, because they work for their needs.
Pick your preferred management plan, then shop for the tool within your budget that will get it done.
