Yogurt makers are simple appliances. They keep your milk and starter culture at a perfect temperature band, usually 105°F to 115°F, for a fixed time, usually 6 to 12 hours. During this time, the live bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus) convert lactose into lactic acid, which thickens the milk into yogurt. You can do this in a warm oven or a slow cooker, but a dedicated yogurt maker makes it effortless and consistent.
There are three main types of yogurt makers you'll see on Amazon. The first is the 'dedicated jar-based' machine: it comes with several small glass jars (4 to 8 jars). This is the classic beginner setup. You can take one jar to work and you don't have to split a large batch. The downside is that jars can be small if you have a big family. The second type is the 'single-container' machine, which makes one big batch (1 to 2 quarts) in a single tub. This is great for making Greek yogurt in bulk, but it's less convenient if you want portion control. You'll have to scoop and store it in other containers. Third, there's the 'multi-cooker' like the Instant Pot. It's not a dedicated yogurt maker, but its 'Yogurt' mode does exactly the same thing. It's a great choice if you want one appliance that does 10 different jobs, and it's the best pick for people who are short on counter space.
For beginners, I usually recommend the jar-based machine. It's forgiving, and it forces you to portion your yogurt, which gives you a feeling of success. But if you want to use an Instant Pot for other meals too, that's just as good. What's most important is that your machine is doing the temperature control for you.
Let's talk about what 'beginner-friendly' really means. It doesn't mean a cheap machine that does everything. It means a machine that is forgiving, intuitive, and tolerant of mistakes. For example, a machine that auto-turns-off prevents over-fermentation. A machine with a clear lid lets you check progress without letting cold air in. And a machine that comes with simple instructions means you won't be reading a dense manual.
Some machines advertise a 'Greek mode' or 'straining function.' All that means is the machine has a basket or strainer to remove extra whey. It doesn't actually change the fermentation. For beginners, it's better to make the yogurt first, then just pour it into a cheesecloth-lined strainer for 30 minutes, if you want Greek-style. You don't need a special machine for that.
Also, be aware of the term 'live and active cultures.' Every yogurt maker creates yogurt, but the store-bought yogurt you use as a starter must contain live cultures. Look for 'contains live active cultures' on the label. Yogurt that has been heat-treated after fermentation won't work as a starter.