There is a world of difference between the Chinese/Korean and Mexican strats. The Chinese/Korean ones are terrible. I don't know whats wrong with fender these days. Cort and Yamaha make some pretty decent guitars in korea...others too i'm sure.
However, try them all...thats the ultimate test. If you like the sound and feel of one better than the other, well you have your choice. If your not too experienced with guitars, have an experienced guitarist take a look at them (preferably someone who plays the same type of music you do, and someone whose playing you really dig).
As far as what guitar is better suited to the blues or any other genre, well there is no answer to that. I like the thick warm sound of a humbucker. Some like the sound of the single coil. However, when it comes to
slide playing, a single coil at the bridge position has a nice bitey tone to it. I guess you could call it a "bitey twang" for lack of a better expression. Don't let that be the only reason you buy a guitar. I have a Japanese gibson SG remake with alnico humbuckers and it sounds fantastic with a slide.