I am a total flip flop person, and I have been wondering the same thing.
I've heard a lot about the Teva mush, and I plan to get some.
Be careful with the Tevas Mush and make sure you can find the old style. They've changed the Mush within the last year and the new style (Mush II) are not near as comfortable as the old original style.
Oh my! I just looked up fit flops. I could never justify that kind of money on flip flips. Ouch.
Buy one pair and you'll change your mind.
The Skecher Tone Ups are almost exactly like the Fit Flops, except the Tone Ups seem to have just a tad more space between the foot bed and the straps, so if your feet have a tendency to swell like mine do in the Florida heat and humidity the Tone Ups may be a slightely better option. I love both though. They are worth every penny. I bought two pairs of the Fit Flops on sale online a couple of years ago for about $25.00 each. One pair of the Skecher Tone ups I paid $49.00 for, but then found another pair two weeks later for $19.99 at Marshals of all places. So you can find them cheaper. I go to WDW several times a year (four times last year) and always carry at least one pair of the Tone Ups or Fit Flops. Some styles of the Skecher Tone Ups are not as comfortable as others. I prefer the Skecher Glam Punk Tone Ups with the softer straps. I had a pair with the sequins, but took them back after just a few hours of walking in them at home.
I have some Nike flip flops that I love and I plan to wear them except on rides such as Forbidden Journey in Universal. I don't want my flip flops flying off so I'll have my Teva sandals for those days.
I always just sit on my flip flops on Forbidden Journey. Take them off and hold them in your hand as soon as the CM places you in the groups of four before you get to the moving walkway. You'll have plenty of time to place them in the seat, sit, and pull the restraints down. At the end of the ride, grab the flip flops, and put them back on just before you go down the stairs.
I feel your pain!!! We were at WDW last Sept. right before I had surgery on both feet for Plantar fasciitis! Sneakers only for me then but I'm finally in flip flops again and bought a new pair for our trip in Nov.
Before I developed plantar fasciitis a couple of years ago I lived in Teva Mush, Nike Celso, Reefs, LL Bean, etc. I now require more arch support than those provide, so have spent a fortune trying to find the perfect flip flop. In order of preference I now wear: OluKai Ohana, Skecher Tone Ups, Orthoheels (Tide or Wave), Montrail Molokinis, or Fit Flops. I always choose three pairs among these to carry to WDW.
I recently bought a pair of Yellow Box Biology though which I'm loving and a few months ago bought a pair of Volatile Keralee. I've been wearing the Volatile Keralee alot this summer and truthfully they seem to be more comfortable than any of the others I've been wearing including my beloved OluKai Ohanas, plus they seem to be good on wet surfaces. Here they are:
http://www.shoemall.com/p/volatile-womens-keralee-animal-sandal/