There are many kinds of ice cream machines. Any of them can make good ice cream.
Huge commercial ice cream machines at ice cream factories like Tillamook, Turkey Hill, Blue Bonnet, Breyer, and others can run continuously. They are fully automated, computer controlled, have automatic ingredient weighing, mixing, air insertion, are cooled by liquid nitrogen, and can produce over 1 million pounds of ice cream per day. The advantages of these machines are absolute consistency in the ice cream they turn out and the great quantity they can produce. The disadvantages are that they cost millions of dollars, take a large factory to operate, and require many full time operators, programmers, and maintainers.
The ice cream machines you see at Baskin Robbins, Coldstone, and other small ice cream shops are called Batch Freezers. They are water cooled batch machines that can make a 5-7 gallon batch of ice cream every 10-20 minutes. They will often make dozens of 3-gallon containers of a given flavor in a day and store them in their walk-in freezers, then switch to making another flavor. These machines cost on the order of $40K to $50K. The advantages of these machines are they are fairly compact, can make hundreds of gallons of ice cream per day, and can be operated by one person. The disadvantages are they require water cooling, they cost a lot, and you need a walk-in freezer to store the amount of ice cream they produce.
We have had lots of small ice cream makers over the years. When I was very young my parents had a 6-quart hand crank ice cream machine that consisted of a stainless steel tub sitting in a wooden bucket filled with ice and rock salt. It took about an hour of hand cranking to make ice cream. My father decided to eliminate the hand cranking. He mounted a washing machine motor on a sheet of plywood, hooked up some fan belts and pulleys, and made our own homemade electric ice cream machine. The advantage of this machine was no more hand cranking. The disadvantage is that it took up a lot of space, was homemade, and is no longer available.
As a teenager I used an electric motor 4-quart ice cream freezer with a stainless steel tub in a plastic bucket filled with ice and rock salt. The advantages were that it made a lot of ice cream with no hand cranking and was commercially available. The disadvantages were that I had to run to the store to buy ice, I had to pour the left over salt water down the toilet, and occasionally when I lifted off the lid of the tub I would accidently get rock salt or salty water into the ice cream and ruin it.
There are small electric counter top machines that contain an air cooled compressor that make 1 quart of ice cream. I have one that costs about $400. It makes one batch of ice cream in about 20 minutes. The advantage is that it does not require any ice or salt. The disadvantage is that it is difficult to clean between batches if you are making different flavors of ice cream.
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My current machines and number 1 recommendation for homemade ice cream machines is the: Cuisinart 21 ice cream maker.
The Cuisinart 21 is a small counter top machine that use a tub filled with a phase change material. You put the tub in your freezer for 24 hours to freeze the phase change material to a solid.
You mix up all your ingredients following our recipes. When you are ready, you take the tub out of the freezer and put it on the machine.
You put in a dasher which will mix the ingredients, scrape frozen ice cream off the walls of the tub, and to churn in air.
You put on the cover and start the machine turning. The phase change material wants to melt from a solid to a liquid, but doing so requires heat. The only way to get heat is to draw it out of your ingredients, which freezes the ice cream. It makes 1 1/2 quarts of ice cream in about 20 minutes. After that you have to clean and dry the tub and put it back in your freezer for 24 hours before you can use it again. That is, unless you have a spare frozen tub in your freezer, or another machine and tub.
I have 6 machines and three extra tubs. I keep all 9 tubs in the chest freezer in our garage all the time, so I can make 9 batches of ice cream at a time.
The advantage of the Cuisinart 21 is that it is very simple to use, compact, does not require ice or salt, and makes great ice cream. It costs about $70 on Amazon or from Cuisinart. Sometimes you can find them on sale for $50, and I have found three of my machines at thrift shops. The disadvantage of the machine is that you have to have enough room in your freezer to store the tubs.
All of these different ice cream machines work well and can make fabulous ice cream. All of them have trade-offs in cost, complexity, ease of use, etc.