With Jackson, you have to pay out the ass to get some quality. Their mid-range guitars are fairly shitty compared to Ibanez or Schecter, and their lower end guitars are pure shit. I own a DX10D that I got a long time ago through musicians friend. It was cool at the time but I outgrew it quick. It started hindering my playing if anything. It's really a rather shitty guitar. This is a pre-fender one too. I can't imagine what the entry-level ones are like now. I've heard they've improved, but I have my doubts.
If you have the money, go for an ESP (not an LTD, an ESP), custom shop Jackson (or an SL-1 or something), or whatever.
If you're spending 1000+, it starts not to matter so much at that point as you can get anything you want really.
But I think Schecter is definitely the way to go with 7-strings, and you can't go wrong with an RG7 either.
Carvin is another one to look at too.