Neither of these were cheap, but DH and I both love our Diaper Dude (for him) and Petunia Picklebottom (for me). We both have the attitude that we carry it, not the kids, so it should look like something WE want to carry (i.e. not covered with Mickey Mouse or whatever). My PP is gorgeous--I get compliments on it all the time from non-moms who want one--and super practical. It carries lots, has very handy compartments, built-in (but removable via velcro) changing pad--you can actually put it down, fold out the pad, and have little pockets with your diapers, wipes, etc, exposed right there under the pad flap. It comes with straps so you can configure it as either a backpack or shoulder bag, then shorten the shoulder strap to attach it to the back of your stroller. It has held up great through 1 kid (almost 3 yo), and is now ready for round 2 (due in April), looking no worse for wear. It is, however, quite girly looking--nothing DH would carry on purpose.
DH carries a Diaper Dude, which has also been great. It looks like a messenger bag, carries most nicely on your back over one shoulder, but can also do as a shoulder bag. Also good compartments and comes with the changing pad. I like mine a little better, he likes his--he's a much more bare-bones, bring a diaper and some wipes and that's enough kinda guy, whereas I tend to want to be ready for a 10-day overland trek just to run out to the drugstore, lol! But in any case, I'd definitely go and look at a bunch, and decide on your personality and what seems to work best with what you do and how you live your life. GL!