I'm not interested in why or why not to use a sippy. DS can drink from a cup with help, but I like having sippy cups too. We have a couple already and definitely do not like the NUK because we have a really hard time open/closing it. Another one we have (maybe Tommy Tippee?? can't remember) has a 2 part valve system so it's an extra piece to keep track of, but that's not a deal breaker. The Playtex insulated "click" ones are nice though I worry that the "click" will wear out and not seal properly anymore?
Are spouts/straws/lips better? I thought the lip would be better because it's more similar to drinking from a cup, but the only kind I find like that are the NUKs. I'm ready to get rid of bottles and he's fine drinking breastmilk and regular milk from a sippy.