I agree that Trick should be mandatory on all the choice sets, it's just too good to pass up, and there are some situations where you want to de-choice your Latios anyway.
Also about the order, from December stats:
| Items | | Choice Scarf 28.616% | | Choice Specs 26.225% | | Life Orb 18.998% |Scarf is the most used, narrowly followed by Specs and then LO. For what its worth on the ladder is see scarf all the time and specs rarely. I do agree that scarf is probably the worst of the three sets though, so maybe it should be third anyway.