Hai dear, from what I've gathered, Dr. Brown's Wide Neck and Pigeon Wide Neck are among the popular choices that fit the standard 5cm wide neck size, both are BPA free and food grade, so quite safe for baby. Pigeon especially has that soft teat design yang katanya menyerupai bentuk semula jadi, so babies who are combination feeding tend to adjust more easily. A friend of mine actually switched to Pigeon Wide Neck after having the same issue with Dr. Isla, and alhamdulillah her baby took to it well. You may want to try Sucvent as well, I've heard its wide neck nipple helps with deeper latch, though do check if the diameter matches your requirement before purchasing, dear. Hope you find the right one soon, take care!