I prefer the foldover because it’s not as wide as the Ambler so feels less bulky to me. I think it’s a nice size for the parks. I also thought it was more versatile because if you bought something on the larger side, you could theoretically put it in the zipper part and not fold over the top. It would be a little awkward like that, but allows for some other carrying options in the park. It’s also cheaper than the Ambler.
Things I liked about the Ambler was all the zippered sections and pockets. For me, it bordered on too many little places to put things. If you like structured bags, than the Ambler might be for you!
Hope this helps! Happy to answer any other questions