I saw that "sure" can be pronounced [ʃʊər] or [ʃər] in the dictionary. Here's my audio: https://clyp.it/4gdwhi24 First I pronounce it [ʃʊər] then [ʃər]
I don't know which one should I use, or is this more of a preference? or a difference between regions? some Americans pronounce it [ʃʊər] and some [ʃər]?