well boots with hardly any flex will give you a ton of control, racers basically have no flex and their boots are very very tight. This gives them the most control over their skis. this boots tend to kill your feet for the most part
a boot with lots of flex is usually for park. there is one boot i have tried that had basically two buckles, and it was so flexy that i dont know how you could ski in it. but when you hit jumps, and you get jerked around on landings, you'll be glad. otherwise, these boots have a lot less control but are a lot more comfy
now your not going to be in the park, and your not going to be racing. this put you right in between, you want to be comfortable, nice warm feet and all, but you also want to be able to control your skis well. so you want to have a boot right in the middle.
im 16, i've skied for 13 years, i got my first new pair of boots, and i choose more of a park oriented boot that is not to soft. its great for all mountain skiing, its forgiving in the park, stiff enough for carving, and just comfy when getting jerked around in trees and what not. i wouldnt exactly suggest this boot for you (its the Dalbello Rave), but i would suggest a boot like it. your going to want to find something thats really stiff, but also really comfy. a good liner and what not. good luck man, thats all i know, sorry i cant suggest anything specific