Totally up to the individual..
I had an Isoki bag for my first 2.. Gees it was heavy to carry.
With my 3rd I spoiled myself and got a Marc Jacobs baby bag and a year later and I'm still in love with it. On day when I don't need it I get a bit sad thT I don't use it! I will keep using it forever and ever, it wasn't cheap but it's my fave purchase ever!