believe it or not boots are important. I use to not think so, but after upgrading to two new boots in 2 seasons i'm a firm believer.
Now I know its gonna be a question so let me answer it for you. There is no single boot that is 'the best'. Every boot is going to fit a persons foot differently depending on length, width, size, etc... So if you go looking for new boots make sure to try a bunch of them on, its going to depend alot on how wide your foot is, to what boot is goign to be good for you. Your gonna want something that is very snug, so that you don't move around in it when u ski. If you end up getting a good boot that fits, this will give you more control over your skis, and will help prevent injuries.
How you ask does this give you better control. Well if you are a bit looser in the boot then when you try to turn or spin, you are going to have just that little extra space where there isn't direct contact with your leg and your shin or calf is going to smash into the boot, so it isn't going to be moving directly with your foot. If you have your boots tight, your going ot have direct contact with your legs allowing your foot and leg to move directly with your ski. I know this may not sound like much here, but it makes a difference. I mean bascially your skis and feet are doing most of the work for you when you ski.. and your boots are holding your feet.... then there is the whole other case about custom insoles.
Long story short if you can't stand to read all of the above.... boots make a difference, spend the money, get some good ones, it'll pay off.