It depends on how soft you want your skis? Halos are softer than Alpha 1's but I personally think a stiffer ski is better for all mountain carving! There both excellent park skis for sure. They both have the same lengths 170, 176, 182. Dimensions are the same on the Halos and Alpha 1's they vary 1mm as you go up in length!
170 cm - 5'0"-5'5"
176 cm - 5'5"-5'10"
182 cm - 5'9-6'5" or above
Happy shopping..let me know if you have any more questions?