The short answer to your question is the YOGOURMET yogurt maker, definitely my favorite (and I've had two other kinds).
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If you want more details...
I posted most of this in another thread... I don't know how to post a link to it, so I just copied it for you (and added a few notes):
If you want to save $ and have the very freshest possible yogurt with no additives or sweeteners...it's very easy to make. Another advantage is that you'll get Vitamin D, which is not in many commercial yogurts (it's typically only added to milk sold for drinking). Also...when you first make yogurt, it does not taste sour, it is almost like cream. So you don't need any sweeteners. I just usually mix in fresh berries, vanilla or almond extract, and top with almonds. Or if I've run out of berries, I use canned pumpkin, cinnamon or pumpkin pie spices, maple syrup or brown sugar, & toasted pecans. I also add a spoonful of ground flax to these.
You can make yogurt without a yogurt maker, but the time would be quite variable and you'd need to find a reasonably warm spot. I think if you're going to make it, it's worth the convenience of knowing exactly how long it will take. I have the Yogourmet yogurt maker (Amazon sells it, as well as other retailers). It makes the whole batch in one big container. I also have a spare container, so I can make the next batch before the first one runs out. I would avoid the ones that make yogurt in individual cups...where would you put your fruit?
You start with milk - pick from non-fat all the way up to whole, or a combination you can't usually find in a store, like half non-fat and half 1% to make a 1/2% yogurt (that's what I often do). You could also use a fresh farm milk if you have access to that (my CSA delivers it). The more fat, the more the yogurt will "gel" on its own. I make two quarts at a time because our family goes through it so quickly. Put the milk in the microwave and heat 'til it JUST bubbles (mine takes ~20 min). Take it out to cool. Remove the skin that formed on top. If you like at this point, options are to add 1/4 cup dry milk per quart (extra nutrition) and/or 1/2 envelope of plain gelatin per quart (that has been softening in a small amount of water while the milk was heating). The gelatin will make it thicker and more "set" if you prefer that consistency (especially helpful if you use very low or nonfat milk). After 1 to 1.5 hrs (depending on ambient temp) it will be cool enough - check with the thermometer in the kit, or your own (~100 to 112 deg)- to add the starter...which is simply a large spoonful of your last batch! (or a commercial plain yogurt with active cultures, if this is your first batch). You don't need to buy those dried envelopes of starter. Just stir some of the warm milk into the spoonful of yogurt in a small bowl until it is reasonably thin, and pour back into the milk. Put all in the yogurt container (you can pour it through a strainer to catch any leftover skin or dry milk clumps if needed), place in yogurt maker (with some water up to line of the outer container), and five hrs later it is done. Put in refrigerator.
If you like the thick "greek-style" yogurt, you can drain this with a strainer/cheesecloth or a "yogurt cheese" kit that you can buy (which is basically the same thing), for a few hrs. If this is the intent though, do not use the gelatin when you make the yogurt.
