My tuppence worth.
Both Trina and Sunpower make good quality panels.
If price was not a problem, then I would choose the Sunpower because:
1. It is a little more efficient, and therefore the panel area is ~8% smaller for a given output.
2. It is little lighter, therefore ~6kg less loading on the structure;
3. It's frame is 10mm thicker, implying a bit more structural strength.
You should note that the operating voltage for the Sunpower is 75V compared to 41V for the Trina. I think this limits your option of series connection (if you particularly wanted to do that).
If the price difference is REALLY huge, then I would be happy with Trina panels.
SV Stella A54-154