Full fat every time! I've greatly reduced my glucose levels and lost a fair bit of weight on my LCHF diet. In fact I've eaten a highish fat diet most of my life, and the only low fat I was ever willing to consume was skimmed milk.
High carb diets are more likely cause weight gain than High fat ones, but if you eat both high carbs and high fat foods then that is going to be a pretty lethal combination, and I think, in retrospect, this may have been part of the reason why I eventually started to put on weight.
Robbity