In all honesty, I myself couldn't say for sure. You hit the head on the nail, both of those PC's are right for you. I'd need to know more specifics about your workloads to make a recommendation between the 2. And nothing will be like finding these at a retailer, and interacting with them yourself to get the "feel" of each. But I can guide you to the best and most efficient option.
If I were to ask you if you prefer to have 1,000 tabs open in chrome, play for 1,000 hours on WoW, or play in 1000K beautiful graphics on WoW, which one of the three would you pick?
If I told you you could have your WHOLE computer on one drive, meaning you lose everything if it breaks and isn't backed up. but it would be WAY FASTER to copy a file, or work with a 4k video timeline without lag OR you could have 2 drives, and MORE total space, where windows and your apps are on the really fast drive, and you have a built in drive to store pictures music, and even apps, like the sdcard on a phone. which of the two would you prefer?
A few key differences and a final thought:
The difference between 16GB and 32GB of memory is negligible in your use case; I feel you won't even utilize the 16GB, and the upgrade to 32GB is dirt cheap if you want 6,000 tabs in chrome instead of 2,500 later down the line for any reason and I can SAFELY assume the memory in the alienware wil be better wuality over the XPS, and if you ever need support, alienware is premium support for free for the duration of your warranty, dell consumer support is more of a free support for a premium, if you catch my drift
😉
The XPS has a touchscreen, and the Razer doesn't;
but, The Razer has RGB, while the XPS doesn't. I know this doesn't sound like much especially if you've never had RGB's. Until you're laying in bed with the lights off, typing on a keybaord that is illuminated in your favorite color out of 16MILLION. Or you set it on your desk and activate the rainbow effect
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Both charging ports are on the same side on the back on the Razer, whereas one of the ports is moved forward on one side of the dell, this may be inconvenient.
Finally, I KNOW FOR SURE the razer will charge from both sides, If the model you get from dell, is not the EXACT one I suggested, it is likely it will not charge from both sides, as it is currently the ONLY one, the same is true for the Razer; ONLY the 13 supports this new technology as of now.
THERE ARE VERY FEW laptops that meet your needs, and personally, I'd be genuinely surprised if you wren't satisfied with the razer specifically, and if I was working with you, in a professional capacity (i.e. you were one of my real life customers) I'd go so far as to offer to purchase it back from you, if you didn't love it. (this isn't an offer to purchase it from you, insomuch as it is to represent my level of confidence, in that it would be the best fit, available currently.)
Unfortunately, neither of the 2 you've chosen in your last post will support the type of functionality you need, and you would be pretty limited to the 3 I linked, specifically; or you'd have to decide on one of the 2 you've chosen and a dock. If the 13" screen on the razer is too small, you could always get an external display, which would, plug directly into, and operate from the same port on either side of the laptop, or even operate over WiFi thanks to the better GPU using WiDi (Wireless Display) giving you more flexibility without the need for cables unless you want them, This is a benefit of the better GPU as well because it can drive, for example, your WoW on MAX settings, in 2K/4K60FPS resolution, on a Large TV or projector. Or you can rely on the 13" screen when mobile, and then throw it onto your 4k 60" when you get home, or plug into and display device, and so on. You have multiple ports, want 3 monitors, go ahead, that GPU can handle it while sleeping. Want to save power, and have the battery last longer? switch to the integrated graphics on the beefy i7 and you can still run wow with decent settings and great performance for a good hours on end. You could put this in a small purse, or a large pocket, or i'd recommend a messenger bag; you could fit the PC, a type c charger, and the external displays i'll recommend in a moment, a couple of external storage drives, and other accessories like a full size mouse/pad and keyboard, portable battery (to charge the razer), and even a car charger and more,ALL, in a say, single targus 15" laptop bag:
https://us.targus.com/products/15-6-inch-laptop-messenger-bag-tcm004us .
In summation I think the Razer 13" and an external display would be the best option. If you didn't want portability I doubt we'd be discussing laptops,
For a display, I'd recommend something like this (this is powered by the port, and will drain your battery more, and that can be offset by putting the built in display to sleep when using it, managing brightness and so on.):
https://smile.amazon.com/ASUS-ZenScreen-MB16AC-Portable-Monitor/dp/B071S84ZW7/ref=sr_1_20?keywords=usb+c+external+display&qid=1582405769&refinements=p_85:2470955011&rnid=2470954011&rps=1&sr=8-20
or this (this one has a built in battery, and wouldn't drain your laptop as fast.):
https://smile.amazon.com/ASUS-MB169B-1920x1080-Portable-Monitor/dp/B07J4SX1MS/ref=sr_1_35?keywords=usb+c+external+display&qid=1582405783&refinements=p_85:2470955011&rnid=2470954011&rps=1&sr=8-35&th=1
Finally, take a gander at this:
View: https://www.youtube.com/watch?v=VOVvO5wtzVU
and compare the settings in the beginning of the video to what it looks like now when you play WoW. That is what you can expect to see, and TBH, when you're that close to the device, EVERYTHING looks better on a smaller high res display
😉 If you can find one at a retailer near you, I'd highly suggest, going over, and tinkering with it a bit to see how it feels IRL. Based on what I can infer about your use cases, I'd wager you're usually at a desk when playing wow and would be able to have a larger display available to plug into, and typically not in the car playing wow per-se; however with the razer blade stealth, you could play it in the car over a mobile hotspot well ( I do this alot myself). I wouldn't go raiding on a trackpad of course, but you can get some real questing in, even on a 13" screen, while waiting for your tire/oil change/doctors office/etc...
😉 All the while charging the whole thing from a portable power bank, car charger, or anything, really, USB-C is pretty great
😀
I almost forgot to mention, a 13" display will probably last FAR longer on battery power. Just because the display is built in, doesn't mean it has to be the MAIN display device
😉
I hope you can see why I'm so passionate about it now, because I want the latop to meet your needs, and I fear you've never actually "experienced" WoW. This is based on the assumtpion that you currently have something like a macbook or the like, because it is metal, and charges from both sides with a dock, and that's a very niche market. This leads me to believe your current hardware is woefully dated. And you'd likely be replacing the dells either due to obsolescence or with a dell, hardware failure, much sooner than the razer. Life expectancy something to the tune of 3 years with the dell, closer to or more than 10 with the razer before you'll be upgrading.
In summation, I think those recommendations are the only 3 options that you "won't" be disappointed in/regret purchase/etc.
) That said, I keep seeing negative comments about Dell support. Have you found that to be an issue? According to the Dell website the XPS15 is no longer offered for sale on their site, but I think 
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