I've been using a Tamrac camera backpack for a number of years and have found it to be comfortable, tough and well made. They have a number of accessories should they be needed. Whatever you decide on, i would get a bag with more capacity than you think you need and if it is a backpack get one that is adjustable to your size. An illustrated catalog would be helpful in making a choice and if you intend to travel with it be sure it will fit in an overhead bin. the model I have is the 787 that easily accommodates a couple of MF cameras several lenses, filters, light meter,30 rolls of film and a Gortex shell just in case. It is easily reconfigured for large format or 35mm.

http://www.jeffreyglasser.com/