Cooper loves his straw cups. He was just too lazy to figure out the coordination. I think he really just had a better association with the straw; having gotten quite skilled at stealing my smoothies.
"Parenting is a constant struggle between making your kid's live better and ruining your own." Willie Robertson, 'Duck Dynasty'
My LO's like both but I've been using straw cups. I found some on amazon that are great, the Oxo tot straw cups. They are pricier than others but I love them and my LO's have no trouble sucking liquids from them. However they don't have a valve so they do spill a bit if tipped upside down. The top of the lid twists close to hide the straw when not in use and prevent spills.
Re: Straw vs. sippy
Pretty much this, she still doesn't understand the sippys even though she likes for us to hold our cups up for her to drink from.
Even a minor event in the life of a child is an event of that child's world and thus a world event.
"I'll love you forever,
I'll like you for always.
As long as I'm living,
my baby you'll be."
ETA: added link