Wiggy has beaten Sheppard at every event they have ridden together so on performance alone he should go.
Sheppard has failed to shine at the junior level (only 4 podiums this year 2 wins and two 3rds I think), and as mentioned at the most recent event the supertrial Alexz beat Shep on the day.
BTC much the same, don't have the stats to hand.
At the beginning of the year Alexz made the difficult decision that he couldn't self fund the WTC but was ranked 11th,Sheppard 6th in juniors. Jarvis rode in the tdn team for 3 years I think when not riding wtc so cant see the logic?
Everyone has their favourites, mine is clear, but based on results/standard of riding.