yeah i agree i have avent ones and they are great
screw top lid can't be popped off
does not leak no matter what
can't chew the top till it leaks
bit expensive though

I also like the ones i bought from target they are a bit bigger type of cup with a straw that flips open it does not leak and ds does not chew at it either. Can't remember the brand and its not on the cup but i really like them i got 2 for $10. So i now have 5 of them lol

HTH
Nikki