I have tried so many things. My 2 year old will drink water from a tea cup, drinking up, bottle with a spout or straw, but if I try to get him to drink milk from anything but his beloved born free bottles (with nipples), he refuses it and keeps throwing it on the floor. I seem to have tried everything, except the cups with straws because I am not sure if this is a good transition (nipple to straw).
As a speech language pathologist, I encourage straw cups over sippy cups! Spouted cups require generally the same oral motor skills as drinking from a nipple. The tongue is positioned forward under the spout.These sucking patterns are more immature and may actually impede the development of a more mature swallow and speech patterns for some children. Also, spouts are larger and require less lip tension than a straw. Straws promote keeping the tongue in the mouth; good lip, tongue and cheek strength and better oral control and coordination. These are all prerequisites to a mature swallow and good articulation skills.
Your child may tolerate changing milk from the bottle to a straw cup readily. If not, you may want to introduce the straw cup and have all the bottles disappear. Use of bottles and pacifiers extended far beyond the first year, promotes immature swallow patterns, impedes oral motor strength, and leads to changes in dental alignment and facial shape which negatively impact future speech development for at least some children.
If you are not ready for a dramatic change, you might try diluting the milk in the bottle with water and offering the undiluted milk in the straw cup. Some of my parents have had success with this method.
I would take him to the store and let him pick a couple of cups for milk, "Which cup looks the best for drinking milk?". Then at home, give him an option between the cups, "Would you like milk in the red or blue cup?". He may be more likely to drink milk if he has some control over what he drinks it from.