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"Let destruction rain!" from Asbel Tales of Graces f
Stop. Don't be in a rush to overpay for something dumb and be stuck with it for years.
Buying a low end piece of junk and then trying to upgrade it is a very, very bad idea. They come loaded with so many cheap junk parts that in order to upgrade them to a respectable $750 gaming computer, you'd expect to spend perhaps $500 after the initial purchase for either of those.
If you can replace the power supply (which you'd need to, as the power supply in both of those is junk), then you can build your own. A $750 budget will get you something much nicer than either of those. Or if you're inclined to add to the budget sometime later once you have more money, it's probably best to wait until you have the money and then buy everything at once. Paying for one part only to toss it out when you upgrade shortly thereafter is highly inefficient.
Are you willing to assemble parts yourself (which saves you quite a bit, by the way), and just don't know which parts to buy?
The only reason to buy a prebuilt like those is not knowing any better. Companies that build prebuilt computers know that their customers are clueless, so they pick parts on the basis of what clueless customers are most likely to be willing to overpay for.
The ideal solution is to build your own, especially if you're on a tight budget. That will typically save you 10%-20% as compared to having to pay someone else to use a screwdriver for you. The case and motherboard will come with very detailed instructions, and all you have to do is read the directions and follow them. If you're willing to do that but just don't know which parts to get, I could pick some out for you.
If you can't or won't do that (in which case, you'll also have to scrap your plans to upgrade the computer later), then the next best thing is getting a computer built to order from a site that will let you choose the exact parts. Some sites try to make it look like they're giving you a lot of options, but don't let you pick some important things or only give you bad options. A site that lets you pick the exact power supply (brand name and model, not just nominal wattage) will probably give you decent options to choose from.
Well, their are things I would not do here, I would update the case, cooling, and prob thermal paste, if I was ordering. I put the cheapest video card they had on it, since you said you would update it later. The power supply will be good for the upgrade. So here is something off of AVA Direct. It is a little over, but you won't have to upgrade the PSU, just video card. It is $812
Well, you can go and check out the site, I would get everything you want, if you don't want to build it, minus the graphics card, if you are dead set on upgrading that later.
I am going to be building one soon, I have never done it, most I have done is replace stuff in my computer before, it is hundreds of dollars cheaper usually to do so. I am looking at building something around 900-1200, depending on my final video card options and a few other things, and it is roughly $300 cheaper, when I priced it out. I live kinda near a microcenter, so that helps some for comparison shopping on the cpu and some other things.