What is the best walking sandal?

Travel Info
I'll be in Europe for 5 weeks and wanted a comfortable pair of walking sandals. I have looked at Keens, Chacos, Crocs, Birkenstocks.. what would be the best choice?

Also, reccomendations for clogs will be ok too. Thanks.

Travel Tips

I actually own all of the shoes you mentioned and Chacos are the absolute best. After you walk around for a few days in sandals, your feet begin to expand, and sandals that fit perfectly to start may begin to be tight. With Chacos, though, the straps are completely adjustable, so no matter what happens to your feet, the sandals will still fit. The footbed also provides support for your arches and heel, which will really start to matter around day 3. Also, when you are wearing sandals around europe, they will get dirty, and you can wash your Chacos. I actually took mine into the shower with me so they didn't get all crusty. I have worn Chacos on my last two European backpacking trips, and loved them.

Keens would be my next choice, then Birkenstocks. Crocs really don't provide that much support and they are bulky for traveling, but you could bring them as a secondary pair of shoes. Just make sure to wear them on the plane and times when luggage might be an issue.