Due to foot problems, I had been wearing Birkenstock sandals for a couple of years then one day my foot doctor turned me on to Crocs.  They looked kinda funky but I tried them and quickly fell in love with them --- they are cheaper than the Birkenstocks and they feel better.  However, the Birkenstocks last a lot longer --- I never did wear out a pair of Birkenstocks but I have worn out 4 of 5 pairs of Crocs (the tread on the bottom becomes slick and is no longer good for slippery/wet conditions)