I have the Chaco Z1/Colorado Sandals(in Eden--a pretty blue/green). I've previously owned three pairs of Tevas (classic/original, Terradactyl and Terra Fi), pand a pair of Birkenstocks (Arizona-the kind without a backstrap). I can't stand anything wrapping around my big toe, so I got the Z1's instead of the Z2's, and they're incredibly stable.
The Chaco's are my favorites ever-- the unique strapping system they use holds that puppy on there no matter what, and since there's no velcro, it won't slip at all even after being wet for hours (a problem I had with my Tevas). Instead of using multiple straps, the Chaco's only have one long strap that makes each section completely adjustable without having to add a lot of bulk for buckles, velcro, etc.
One of the problems I had with the Tevas was they took a long time to dry and in the meantime the straps and rubber bottoms would rub my foot, plus my foot would slide around on the sandal slightly. I've had the Chacos on in a creek, a lake and a pool and they've done great--they dry fast and hold my foot still.
Best of all, I can wear them for long periods of walking without aggravating my back pain, which both the Tevas and Birkenstocks tend to do.
I did look at the Straprunners at the Nike outlet before I got the Chacos, and I liked them a lot--if I hadn't liked the Chacos so much when I tried them on, I'd've gone back for the Straprunners. But I had a big ol' dividend certificate for REI burning a hole in my pocket...
Whew! I can go on about stuff all day...