Neale,
They are both good options as Trina and Jinko are very similar in quality and performance and have the same warranty conditions. In this case I would lean towards the 315W Jinko as it is a slightly higher (5W) rating and uses half cells which will perform better if partially shaded and should be less prone to hot spots over time.
However if these 2 panels are from different installers I would go with the installer which has the best reputation and will hopefully install the system to the highest standard.
Hope this helps,
Jason