What's the best yarn for making baby blankets?

Our members have hundreds of years of stitching experience and my personal experience is 50 years! Hope I can help. I suggest you first recognize your skill level. If you are just starting out, using baby sport or yarn can be a challenge. These yarns produce a beautiful lightweight to airy (depending on pattern) finished item. The lighter weight yarn can be a little harder for a beginner to use (like a child learning to write with a no. 2 pencil; usually the learner does better with a thicker pencil because it's easier to grip and control). 4ply, worsted weight yarn and sport yarns are usually used in making afghans. It's perfectly okay for baby blankets, especially if you are making one that is crib size, or one you'd like the baby to use through childhood. I agree with some of the suggestions you were given by others about yarn brands. Caron Simply Soft yarn is great to work with, very soft, but it does tend to stretch more than I like to see in a blanket, especially when the item is large. Caron "Paints" doesn't seem to have this result. It tends to hold shape better. I love working with Vanna's Choice by Lion Brand. It is uniform, has good substance and workability and has produced very acceptable mittens, hats and afghans for me and is a good value for the money. I can say the same about Bernat yarns. Red Heart is an old standby. Their TLC is preferrable to the regular 4 ply worsted (it is a bit rough), but any yarn will soften up when machine washed and dried and softened with dryer sheets or liquid softener. Remember, follow manufacturers' directions about laundering (I include them with the gift, and a lingerie bag for washing the item). There is nothing worse than to spend time, energy and money to make a handmade item, and have it ruined because it didn't hold up in the wash! Todays synthetic and some wools are made to be machine laundered, but it doesn't hurt to help a little by using a lingerie bag to protect the item from snags. Even if the item isn't intended for long use by a baby, mom or dad may want to hold onto it for a keepsake and baby might want to use it again one day when she has a little one. Another consideration is fiber content. I recommend using only synthetic or cotton yarn (or blends) for babies. Wools can involve allergies and nylon in a high content can chafe tender skin. Good luck with the project. Be sure to contact The Handiwork Ministry if we can be of help to you. If you are buying your yarn at a yarn shop rather than a discount store or caraft store, you can get support for your work. The store owner or manager is usually knowledgable in at least the basics of knitting and crocheting.