Use regression instead of classification for hard labeled ranking datasets
An issue with regression is that the distance between negative, neutral and positive are not necessarily the same. This transition/uncertainty you mention can be modeled by using a probability distribution over the classes as opposed to a hard argmax. If you use Neural Networks for example the last softmax layer gives you this information for free (For example: 0.1 on Negative, 0.6 Neutral and 0.3 Positive).