Predators in my experience were of poor build quality and tended to fall apart after a few months. Plus they're extremely uncomfortable in the 'wear-in' period. Good for striking the ball i thought however.
Nike total 90's were very comfy, but i prefer the II's over the III's, purely for the aesthetic appeal. Not so good for shooting but excellent boots, they felt like slippers!
Puma Kings are all-round quality boots, in black though as the white/creamy ones look cack.
I now own Umbro's (the style michael owen wore last season) All the stitching etc is still fine after more than a year, only £40 and good enough.
Never tried mercurial vapour's, primarily because they don't look as though they'll protect your feet much, and also because they seem a tad over-priced for the 'amateur' footballer market. (I'm a student!)
Adidas Kaisers or World Cup's are solid boots, I got a pair of Kaiser's for astroturf football and can't complain. Think of them as Adidas Sambas with studs!!!
Asics boots aren't so great though. Didn't really enjoy playing in them.
So my tip is not to buy the most expensive boots. I spent £90 on predators two years on the trot and they fell apart. Nike's are probably the better boot on balance, as are puma kings. Buy Umbro if you want your boots to last