Reef Phantom thong sandals have a snugger top strap than any Ive ever bought, although I will concede that Ive only bought relatively cheap ones in the past.  Also, there is very good arch support, which I consider critical, and they have a thick and well cushioned sole.  They are quite comfortable and sturdy.  Ive only had them for a few days, and as I break them in, I can imagine they may become even more comfortable, in which case, Id give them 5 stars.