I have a Novara bag and really like it, but I haven't used any other so YMMV. I rarely carry my laptop with me but I do have a separate sleeve for it. I usually have clothes and a lunch and maybe some files and book. I have a couple of pairs of shoes I leave at work so I don't have to pack them back and forth.

I have a touring bike with a rack and panniers that I like more than using a messenger bag for anything longer than my normal commute.