Everything that has been documented has been hinting at a central core thought. This is that no matter which model you buy, it really all comes down to your personal preference. While some bike grips will be better received than others, it still only matters what you desire. The same concept can be applied to the size. There really is no right or wrong answer here as some riders will prefer thicker grips while others will prefer thinner.
In addition, what you are accustomed too can also play a pivotal role. Some people really do not like change and if you are one of those people, stick with what brought you to the dance.