It depends on your ability and your preference really. Im the same hight too and I had 166 ar7's last year and 170 rossis this year. I'm going longer next year forsure even though i'm done growing, just because the 170's still feel short.
As for the ar7 vs thall, if your mostly jibbing around go thall, if you hit larger jumps ar7 obviously. My ar7's were stiff in the tails but I could butter the noses pretty easily, so the ar7 is still a fairly good jib ski. Id definatly recommend the ski, light, poppy, excellent durability and a really low swing weight.
Sorry for possible spelling errors, on mobile haha.