Try all the brands on. It is my understanding that Lange widen their boot finally to take in more skiers. It will be argued that all brands are just as good, but I will contend that if you buy a boot only because it is brand X and supposed to be good you will be miserable. Most all brands have three different lasts, fits. Performance is the tightest, intermediate is medium, and beginner is the loosest.
Try To get boots that may seem too short. The fitter will shell fit you and this will change from brand to brand. High performance a tighter shell about one finger too long, new skier about two fingers. Anywhere in there will work. You will be able to eliminate a boot in about ten minutes or sooner because it is too loose, tight pinches, makes hot spots. When you are narrowing in on the right last, you need to wear these around the store for thirty minutes or even longer. If in that time the pressure is uniform you and not hot spots you are in business. There may be two or three boots that really fit in this then you get to start choosing by how much flex, quality of the liner and such.
The heat moldable I feel might be more of a gimmick than reality. The heat moldable boot will mold to your foot by body heat as well and really doesn’t take that long. You boots will pack out quickly so work with a fitter that will refit after packing. Think seriously about seeing someone other then the people you buy from for final fitting and alignment. Alignment isn’t always part of the purchase and you may not need it either. Find a pro that can ski with you a little and watch for alignment problems. If you have some and haven’t corrected it you will be amazed how much easier you ski.
Good boots should and can be comfortable.