For a solid gaming laptop I'd go with the Lenovo Y580 I own one and can attest to it's awesomeness, but if you don't believe me you can always ask White
That being said, it's $1000 which is a little over the budget that you mentioned...
About the laptops you've selected, honestly I've had shitty experiences with both Dell and HP, they just make shitty computers (with Dell's being the worst, their plastic, flimsy and heat up way too fast)
So I have one question for you, are those graphics cards "Intel integrated graphics" or Dedicated AMD/Nvidia graphics cards?
That's kinda the most important part...
If you're fine without a dedicated graphics card, then I'd reccomend the Lenovo Z580 (I have two of these, their just that good)
Their cheap, and pretty damn powerful, and the quad core third gen i7 will handle everything you can throw at it...
The only downside is that the graphics card is the intel integrated....
It'd help a bit if you could specify what kind of games you will be playing... because if you wanna play something like Tomb Raider, Crysis 3, or Far Cry 3 on a laptop at medium settings, you're gonna have to spend more than $700
EDIT: to my knowledge the Dell is the only one with a dedicated graphics card, both the HP's have integrated graphics...
If you can name a couple games that you want to be playing, it'd really help in telling you weather or not you need to sacrifice build quality for a dedicated gfx card