hey man... both are great brands. Unfortunately, I have no experience with those specific bags, but I have two Lowepro camera bags and they are awesome. Also, I just bought my second Timbuk2 bag for my new laptop and they work great.
I think both companies have a good return policy, so you can always buy them and try it out. You might find the Lowepro Classified 250 AW at Dodd Camera, so you can always play with it if they have it.