Have a look at what each trade offers you.What courses you will realistically get from each trade and how you would be employed throughout your career.Of course im going to be partial to arty in that you have a wide variety of jobs to choose from, ie on the guns,in the command post, in the op, air defence, surveyor, locator and the list goes on, but get all the info you can off recruiters and the net and make it an informed decision.