Full fat, for sure. Low fat is a bad idea. Your brain is made of around 70% saturated fat. The thought that saturated fat is bad is just flat wrong.

Here's my yogurt recipe. Super easy, super tasty. I don't make it much anymore, but it was fun while I was on a yogurt kick.

YOGURT ############ Heat up a quart or 2 of full fat milk. Or, use half milk, and half heavy whipping cream, for extra richness - that's what I did.

Heat it to 115 Fahrenheit, measure with digital thermometer Once it's at 115, take off heat, and stir in maybe 1/4 cup of plain starter yogurt I use a whisk to distribute it really well. Then pour into a jar. Put the lid on, and double or triple wrap in a warm blanket or sweater or down blanket or something. It needs to stay warm overnight, or 12 hours or so. After 12 hours, put it in fridge, it will thicken.

Some people heat to 180, and then cool to 115 ( to get rid of competing microorganisms) but in my experience it's overkill, the above works every time for me. And cooling to the right temperature is a big pain.

Also - be sure to put a little aside, before you start eating, so you don't have to re-buy the starter yogurt.