I haven't seen the other brands in the flesh, I have a pandora but mum told me she saw another kind and didn't look as good a quality, I guess thats why the pandora charms are higher cost...
I do not doubt that there are some dodgy ones out there, just thought I might add that the Lovelinks ones are quiet nice, mine has had a few knocks and even with glass beads has not chipped etc. so I think that it is pretty good quality.