Hi there,
I think all babies are different in their preferences. I have tried different kinds but my lo seems to like the ones where she has to suck out the liquid, almost like we would suck out of a straw (and she has to suck fairly hard which is why now I can tell when she is actually getting something).
I have tried them all out myself, but my lo does not necesarily prefer the one that I think is the easiest. I would measure a couple oz into the cup and then measure after to see if your lo got any. It took my lo a while to want to use the sippy cup. She is 10 months and we use it (like you) during a meal or for some water during the day (mostly just for practice).
If I leave it where she can get it, she seems to want to pick it up now and try to use it. She doesn't have much success on her own yet.
shannon