Originally Posted by
HB.Watermelon
This might be a preference thing. But, I'm currently using a messenger bag for commuting, and hate it! It shifts too much when riding. And, all that weight makes me feel top heavy. Do backpacks dig into the neck when riding? Are they comfortable? Or, are panniers the way to go?
Messenger bag should not shift - you need one with a stabilizing strap and you need to wear it high up on your back.
Backpack is similar to a messenger bag - contributes to the "top heavy feeling", and makes your back hot.
Pannier bags are different - they require a rack, lower center of gravity (thus making your bike handle differently), might be less convenient to carry off the bike.
I'd say - make sure your messenger bag is adjusted so that it does not shift. If you still hate it, skip a backpack and look for panniers.
Others may know more though.