Danger, long reply...
Interesting post, everyone has their favorites of course. Your question said that this person is hiking, so weight and bulk are important. If you were talking about an outfitted trip with vehicles, or animals, you could go to Cabelas and buy some of their Outfitter series gear and be pretty happy, but, it's heavy stuff. Making that leap from 3 season to 4 is a big investment in both weight and bulk usually, driving some decisions.
TENTS:
When you go four season, one big problem is that you need a stout tent, it'll have extra poles, heavier material, and perhaps more hefty stakes and guys. For rough conditions, a tent like the North Face Mountain 25 (2-person) or VE-25 (3-person) would be good. They are heavy tents 10lbs+, so you'd split up the poles, body, and fly among 2 or 3 hikers. Most of the time, when I'm backpacking 3 season style, I carry a Sierra Designs Lightning. It's a 2 person (or 1 with pack) and it has a full rain fly. It's free standing, and weighs about 4 lbs. (You can get by with a lighter 1 person tent, but, I've always felt like I wanted to be able to have gear in there in bad weather, so I use a 2 person for myself. That strategy doesn't work well with heavier 4 season tents, because you really want to split the weight with someone.)
PACK:
I currently wear a huge beast, because I'm usually the group leader and typically carry some "extras" with me. My current pack is a Kelty Red Cloud 6650. (Yes, that's 6650 cubic inches, it's a monster). The good news is, you can carry most everything you need inside the pack, including tent and sleeping bag. It really helps in poor weather conditions to have everything contained. This pack has a top that can be removed, and turned into a fanny pack, which I've used at times. I have a "ten essentials" kit basically in the top, so it's pretty easy to grab that and go if we take a little day hike away from base camp. There are a lot of adjustments for the waist belt and shoulder straps, so you should be able to make it ride on you well.
Having said all that, if I weren't the group leader on a trip, I would not wear a pack that big. I have a smaller pack that is about 4000 cu in, and isn't as bulky, it's an old pack from EMS, I don't know what the model was called back then, but, it's much better if you're going to be on mountain hikes, because it keeps the weight closer to your back. It's also great for bushwacking, because it doesn't stick out on the sides as much. Some of the Osprey packs are like this style, and I have seen a North Face Pivotol/Catalyst pack recently that's around 4000 cu in, and looks similar to the one I have. It has an interesting waist/strap system that's supposed to pivot with your hip/back movement. (could be just good marketing)
For an expedition type pack, you might also consider the ones that Deuter makes for NOLS (National Outdoor Leadership School). They are hefty packs, but, they'll take you anywhere. They are on the NOLS web site:
http://www.nols.edu/store/product.php?productid=16400&cat=285&page=1Gregory packs are very well built, and there are a variety out there. They are pretty pricy, but, friends who wear them say they wouldn't buy any other brand.
SLEEPING BAG:
For a sleeping bag, I think you need to consider a couple factors. Do you want one bag, or a bag, and an overbag. Wiggy's, for example, makes an Antarctic bag rated to -60 degrees F. You can get the FTRSS overbag and probably be comfortable to absolute zero! (Ok, don't try that.) You also need to decide if you use down or synthetic fill. The synthetics are getting pretty close to the compressibility of down now, and the weight is getting close too. They will do better in wet conditions also. Still, what do I usually have, a down bag.
I have a relatively inexpensive Coleman -10 degree bag for winter. Most people frown on Coleman, but, their Exponent gear is pretty good (although a little heavier than the competition). It's filled with Primaloft stuff, so it can get wet and still have a prayer of getting dried out in the field. If price is no object, for winter bags, Wiggys bags look good, or maybe a Mountain Hardware design bag.
For 3 season, I use an EMS Mountain Light 20 bag. It's down, very light, and packs very small. It has a Pertex outer shell, so it's pretty good at shedding water, which is key if you're going to carry down. This is what's in my pack about 75% of the time.
Don't forget that you need to have some kind of pad under that bag. I use a self inflating ProLite 4 from Therm-a-rest. Some folks don't like to take a chance with a leak in an inflatable in the back woods, so either carry the repair kit, or a closed cell foam roll-up pad.
I better stop before this gets out of control. It's way too long, and I've only talked about the tent, pack, and bag so far. <img src="/images/graemlins/shocked.gif" alt="" />