I have used the Nuby sippy cups with the silicone spout exclusively as a transition from bottle to drinking cup for my toddler. The cups are nice and big, and easy to hold onto. The spouts are soft and similar enough to a bottle nipple to make the transition between bottle and cup a breeze.
The plastic in this cup contains bisphenol-A, which I have recently been attempting to avoid. I have begun to replace these cups, but have not found one as functional and easy to clean as the Nuby cup.
My only complaint is that there are a lot of nooks and crannies in the spout, which makes it a bit difficult to clean unless you rinse it out right away (and who does that all the time?).
You can purchase several colors, which we did. The tops and bottles are all easily interchangeable, so more times than not the top color doesn't match the bottom color. This is only a concern if something like that would bother you.