Rectangular sleeping bags are the initial and also most typical form you'll see on the market. I directly don't think there is much of a visible difference in between the fillings nonetheless synthetic fibers will certainly not soak up water and will certainly keep you warmer also if the bag is a little bit wet. A damp down resting bag is very hard to dry out as well as is taken into consideration even worse than having no sleeping bag at all.
Remember that with time, from typical use, a treking sleeping bag will certainly lose its warming performance. This results from the fill obtaining a bit much more compressed. This will cause the "air pockets" to go away.
When not utilizing your bag, never ever leave it inside a things bag, always hang it up or maintain it in a loose storage bag. In case you leave it saved inside a small bag, it can completely lower the insulation.