It really depends on if you will BF or FF, sling or buggy, if you are more of a "go out for a couple of hours max but be home for meals and the bulk of the day" type or a "walk out at 9, return around 4, need to carry everything for all possibilities in that time frame". If you are a "walk everywhere" or a "drive everywhere" type.
if you FF the pockets come in handy. If you are out for whole days regularly, then a big bag is very helpful. If you walk, again, being able to carry everything in one bag slung over the handlebars is better, if your drive everywhere, you can always have a carrier bag with a spare set of clothes and some more nappies/wipes in the boot.
once yoru DCs are weaned, being out all day means taking food and snacks, if you are usually home for meals, that's less of an issue.
(I have had a spotty skip hop one and a green "plain jane" by pink lining - I prefer the second and didn't like hte messanger style, I often would have DC2 in a sling so perfered a bag I could carry on the top handles rather than a messanger bag with one long strap)