Performance wise G51j > Envy 15 > XPS 16. The Dell's HD 4670 is the weakest of the group. I haven't seen performance numbers for the HD4830 that comes with the Envy 15, but notebookcheck.net is expecting it to perform better than the 4670. The GTX 260M in the G51 is the best of the group. Since they all come with mobile i7 processors, there isn't going to be a difference there. As far as price, I can't comment since the Dell is the only one with a price tag on it yet (around $1300 base price).