Never tried a rack since my bike isn't truly set up for it. Also, with the cost of a rack and decent waterproof panniers, I figured I'd try a messenger bag first. I used what I had from college last year and that wasn't all that great. No cushion, liked to slide when powering up a hill, too small, etc. I finally broke down and got a Chrome Metropolis after a personal recommendation. I've been using it as a replacement for a laptop bag since January (I travel for work a lot) and finally used it commuting today. What a difference! I loaded with a 17.3 laptop, change of work clothes, clothes for home, towel, jacket, lunch and normal work accessories. It was comfortable, has a stabilizer strap that worked perfectly, held everything I needed and worked just as I'd like. Definitely the right choice for me.