I was considering the Alienware AW3420DW display recently, despite the cost. All of the specs and reviews seemed just fine and I had pored over (what I thought at the time) all other displays that were possible contenders (to me, of course). I was literally ready to order when I discovered someone had released another competing display and had that
REALLY? moment. I thought I had agonized over it enough...
LG released their Ultragear 34GP83A-B display. This display cost quite a lot less than the Alienware. The specs are all equal or superior, execpt for G-Sync. The Alienware display is GSync
compliant (meaning it has the NVidia chip for adaptive synchronization built-in). The LG is GSync
compatible, meaning it does
not, however it has been tested by NVidia and found to perform adaptive sync without issue. If you're an AMD card user, this is an
AMD FreeSync Premium display.
I agonized over this and ended up purchasing the LG. I can tell you that I find it to be beautiful. It adaptive-syncs without problem. I didn't have to "set" anything for the adaptive sync to work - it does so by default. I run in the native resolution of 3440x1440 and run at 100Hz
* easily using my Nvidia GeForce RTX2060 video card. I have run it higher refresh rates (144Hz) without issue as well, but, not feeling the need to go super high, I have moderated that setting (this also reduces noise from the video card). Elite Dangerous is beautiful on this nano-IPS HDR display.
My PC is in an east-facing room of my home where mornings are very bright. I have no issue with brightness of this display, in fact I operate the brightness at 18% (units presumed). Yes- that low. The display is exceedingly bright in my opinion. I can't imagine folks running this things at full brightness, screaming at your eyes for prolonged periods unless you use sunglasses!

Colors are rich and beautiful. This display is rated at 144Hz (vs Alienware's 120Hz), and overclocks to 160Hz.
I won't comment on how it occupies desk space because I generally don't use display bases, preferring to post-mount them and free my desk of that. This also allows me to adjust the display's height to my preference. Most adjustable-height bases are insufficiently high for me.
Have fun making your decision. It's one fraught with worry for some of us.
* Just to be sure (because I don't know your level of knowledge): you
must use the DisplayPort interface for high refresh rates. HDMI only supports up to 60Hz, period. Make sure you get yourself a premium-quality DP cable and you won't encounter any issues. The display includes one, but I opted to purchase one because I needed one that I (correctly) presumed would be longer than the one supplied. I purchased a Kabel-Direkt DP cable from Jeff Bezo's starship-funding store.

If you consider this display, I suggest you look at LG's web pages for info. They have a very comprehensive documentation of the display's features and (more importantly) technical specs that I consider more reliable than third-party marketers' product listings.
Specific questions? PM me, if you like.