It really is all about fit, different boot brands use different lasts [foot model], you need to find the one which is closest to your foot shape. There are plenty of good brands out there – Scarpa, Meindl, Mammut (used to be Raichle), Aku, Zamberlan, Brasher are all good, as are others like La Sportiva, Asolo etc.
A boot that doesn’t fit your foot is instant misery. Go to a well-stocked outdoor shop, in the afternoon as your feet swell by up to half a size over the course of a day, take your own socks, try lots of different brands and buy the one that fits you.
If you have odd-shaped feet, a good boot fitter can modify the shape of the boot to suit using rubbing bars, inserts and so on, Altberg will do this, but they’re not the only option.
If your feet are a particularly weird shape, Altberg can make a custom boot for you, but it’s heinously expensive and most people will fit into a standard boot, maybe with some modification.
Personally, unless you’re going to wear crampons with them, I’d opt for something light and reaonably flexible, but some folk – generally those with the foot placement skills of a hippo – prefer really stiff-soled boots so they can step on anything without thinking 😉
