I personally prefer straw cups to sippy cups since a lot of the sippy's require sooo much suction (try it yourself, you'd be amazed). Also, when you think about it, anytime you go to a restaurant, they give you a straw to drink with so it's much more natural than a sippy cup. This is the one we use and they're great - http://www.netkidswear.com/luvncar14ozf.html. Beware that some straw cups like the Nuby Straw Cup has a wider straw at top, which is not as comfortable and requires the child to bite on the straw to get the liquid out, which is not good. We got rid of these.
My daughter will only drink her milk out of the Born Free Sippy cup. It's shaped like a bottle (with handles) and has a soft spout, which requires much less suction than a lot of the other sippy cups. They can be a little leaky sometimes (probably because of the lighter suction factor). Good luck