I have just 2 packs now. 1 the big Berghuas with the side pouches 120lt or 80lt without the side pouches, and a Granite Gear Ozone. Both very good. I have got my kit down to about 10-12kg on my 1-3 weeks walk abouts so mainly use the Granit Gear, Recomend either. Ref comfort wise, depends on the way you pack your pack. Does make a big difference.
My daughter and i went to base camp and used the UK based KE adventure and found them good. the walk took about 12 days but total time of 18 days for the whole trip UK to Uk. If your iffy about altitude take some pills with you, if your all right no probs if you feel iffy at least you have the altitude pills with you and you can take them and carry on walking. We got off the Yeti Airline plane at Luka runnway to find people hanging around sufferring from altitude sickness and they had been too sick to even go any further up the mountain. Take AMODIUM pills with you . Every one in our trip ended up with the skiters(shits). Warm clothing along with the best sleeping bag you can get your hands on. Its cold at night time. If you forget any stuff you can buy it at a fraction of the cost 2-3 days into the walk at a village every one passes thru. The distance per day is not great but the effort of doing it is. Porter out in front sets the pace. Do it and enjoy the experiance, my daughter and i did. We were both ill, but there again if you have no story to tell its not worth going. Im allways ill acording to my daughter and rereading my diary for the tri[p. But we still go, and remonise just how ill we were. The stories get bigger and bigger.
if this is not a wind up, hills around London for Kili training. How about finding the tallest building near you and putting a heavy pack on your back and start walking up the stairs to the top of the building. Do that for 4-6 hours a day should get you into some sort of training.