I've tried all the brands mentioned and none of them worked for me. For sandals, I stick with Abeos. They are available at the Walking Company in a number of different styles and foot-bed designs to fit and support your foot. Personally, I can't imagine walking in a flip-flop type of sandal for long periods of time, over rough terrain and cobblestones or standing for very long in something that doesn't have much support. So I'm a little puzzled about the ankle strap thing. As someone else said, sandals with Velcro straps are great for adjusting as the day gets longer.
My feet and knees are bad enough that I wear Ahnu boots and support socks for most of the day, no matter how hot it is, and switch to other shoes for later. Depending on when in the summer you go to England, France and Italy and where you go in those countries, don't assume that you will want to wear sandals all the time. It can definitely be rainy or cold in any of those places at least the first two weeks of June. Voice of experience here.
I have these Abeo Smart 3590 mary janes which are very light weight and have a generous toe-box. I had purchased the Abby style, but they were so heavy that they weren't practical for packing. Fortunately, I have some kids and grand-kids that wear the same size shoe I do. These are light, but worked great with or without socks in the UK in May and June. I will wear them out. Sorry kids and grand-kids.
I have a hard time buying sandals because I have broken both my little toes and they tend to stick out in an odd way. They are also very small, so I have to be sure that any straps on the side cover them or are high enough on my foot to let the little guys go free without catching on the strap. I currently have these Abeo Bahias and some Abeo Capistranos which are no longer available, but similar to these Huntingtons. I also have these Brynns. They are very comfortable, but I would never take them as a backup pair of shoes because I don't think they are supportive enough to be worth even their limited weight.
If you have a Walking Company near you, go take a look and try on some options. If not, go here to browse sandals and more.