year 12 easily.
being the oldest in the school and having all that extra freedom of senior school was awesome. then it was your final year so most people had their social groups worked out and there wasn't as much of those bitchy social politics as younger years. everyone is going through the same stresses so bands together, then realise it's the last year you'll all be together so much love throughout the grade.
teachers have you as their priority and put in a lot more effort than in any other grade. they also let you get away with a lot more stuff. academically everyone starts really working hard and performing, possibly because of more teacher effort, but also that it's simply year 12.
constant stream of 18ths
highest stress levels, but highest awesome levels too