For as many brands and types of gear as there is, there are as many, if not more, opinions on what works.  The key is to find what suits you.  In the end, it's always worth remembering that there have been some remarkable things done in gear I'd be scared to take my dog for a walk in.  Having said that, the equipment you choose to use can mean the difference between a miserable and brilliant trip, an early finish (try skiing over the icecap with a tent ripped in half), and in the extreme, life and death. 
Below you'll find some of my thoughts on gear.    In the real world of expeditions, I don't believe it's possible to stay comfortable the whole time- at least a little hardship goes with the territory (and perhaps the sick part of ourselves that keeps us coming back for more wants it this way!.  Through trial and error over years of cold, wet and sometimes miserable expeditions to lots of cold places, I've found (and continue to search for) equipment systems that make all the difference. 

Boots

• alpine
  I've never worn plastic climbing boots.  I started mixed climbing in a floppy pair of leather boots and went from there.  The new(ish) generation of technical leather boots offered me the comfort to walk-in and the precision on rock, ice and mixed ground.  The trouble was, after wading through wet snow on the trudge back to basecamp, my sodden boots didn't exactly call out to be put on again, particularly the morning after when the cold nights had frozen them solid.  The compromise was to glue on a full gaiter- that is, one that covers the the entire boot.  The Extremities Terragaiter was always my choice.  However, the whole package was a bit heavy and the 'bagging' loose material was clumsy.  For me, the appearance of the Scarpa Phantom Lite was nothing short of a revelation; to me almost the perfect alpine boot, it's both extremely light and trim, at the same time as being very technical; excellent on all types of ground.  The new GSb system that attaches a Grivel crampon onto the front of the boot by a single hook further refines the system and moves further towards my ideal: technical equipment pared down to only that which is truly useful. 
• polar/icecap crossing
  The boots you choose to wear will be dictated by the ski bindings you use.  Between Berwin, cross country and telemark/nordic bindings there are different camps that swear by each.  I use a telemark binding and so boots with a 'duck bill'.  As well as being warm, the boots must handle internal moisture and also perhaps wet snow conditions (and even water on the Arctic Ocean).  In my experience, it's extremely hard to stop a boot from becoming wet over time from sweat.  Vapour barrier socks (basically plastic bags) worn between a thin inner and thick outer sock are well worth considering.  It should be noted though, that you really need to take special care of your feet if using VBs- fully drying and powdering them every night.  The Modre Extreme boots, based on those originally worn by Amundsen are successfully used by many teams, but it's worth noting that they're anything but water resistant.  Together with Scarpa, I designed a modified Phantom 8000 boot, a high altitude mountaineering model, that has a flexible telemark sole.  On our last North Pole trip, it seemed to work well.  If you're interested in using these boots, please contact me to find out about availability.

Clothing
What to wear in an environment that can differ so drastically?  One day it's 'warm' and raining; the next it's sunny but bitingly cold.  Clothing choice is perhaps the biggest question that can effect so much on your expedition; from a question of comfort all the way to your ability to complete that steep north wall or reach the West Coast after 25 days sled hauling .  It's also the area where I believe there's a great deal of hyperbole put out by many manufacturers who have invested huge sums of money in fabrics and systems that in practice don't really perform.  So what systems do I use?  It really depends on the type of activity in which I'll be undertaking.  Critical factors like weight, packability, versatility and robustness all come into the equation; when you've only got one rucksack or sled, every ounce and little bit of space counts. 

The softshell system has been used in various forms for many years and it's the one that my clothing sytem is based upon.  Whether running up a snowy peak, plodding away on a polar crossing, or inching my way up difficult technical climbing, there are very few times I resort to waterproofs.  They cartainly have a place in my rucksack and sometimes sled, and 

Arctic Alpinism & Climbing
Technical Ascents  When the climbing gets so difficult that belay duty and pitched climbing mean there's less body heat generated,