Slazyel

out of those 3, the g7

What?!
Samsung G7 it is then hahaha
 
The Samsung G7 is $899 for me...
The ASUS VG27AQ1LA is $429 (no stock)

The DELL is actually a decent 27" IPS monitor -- my brother has two of them (his work paid of them...because COVID WFH).
https://www.rtings.com/monitor/reviews/dell/s2721dgf
 
My suggestion, if you go bigger than 24", get 1440p, because when the monitor is that big, the pixels starts to get...pixelated with 1080p at that size.
TYPICAL VA panels have a lot of motion blur, but Samsung did some kind of wizardry so the G7 DOES NOT have this problem -- probably why they are charging $$$.
IPS panels have poor contrast vs VA.
 
I ended up upgrading one of my 24" ASUS 144Hz 1080p TN (MG248QR) panels to an ASUS 27" 1440p IPS (XG27AQ), it was a huge difference.
(after seeing how my TN panel looks like peasantry compared to my brother's DELLs).
 
What is the availability of the ASUS TUF Gaming VG27AQL1A in your region?
It is a decent panel for the money, and it is an improvement over the older ASUS TUF VG27AQ.
https://www.rtings.com/monitor/reviews/asus/tuf-gaming-vg27aql1a
(I was actually waiting for this to come back in stock locally....but no luck)
 
Personally, 1440p beats out a 1080p, doesn't matter if it's a 1080p 360 Hz or some ridiculous number.
1440p 144 Hz / 165 Hz / 180+ Hz is more than enough these days.

Mostly depens on your rig, your games/usage, and the resolution and size you'd prefer...

One of those is 1440p and the other two 1080p. That's a pretty drastic difference and you need to decide that first. It'll heavily come down to what GPU you have and the games you like to play. 
 
If you decide on 1440p and you have the GPU to back it up, the Gigabyte M27Q-P / M27Q Pro is a great deal for $270 US. 
 
 

The Acer is only FHD, smaller and 240Hz is only useful if you can reach it, it's a monitor for competitive FPS mostly, and cheap
The Asus has same usage but is bigger and even faster refresh rate, so more expensive
For a more varied usage the Samsung G7 is way better being WQHD 240Hz - so is quite more expensive-, but with something slower than a 3060 you may struggle getting frames

Do yourself a favor and don't buy anything 1080p with a 3070Ti. Its just such a low resolution these days and you have a GPU that's far more useful for 1440p. 
 
As for what to buy, I linked the best roundup you're going to find of what is good these days.

This is a weird trio to compare. The only thing they have in common is the 240hz refresh rate, but unless your main focus is playing competitive shooters at a very high level that's pretty useless. 
 
The Acer is 24" 1080p, that's basically entry level. It has nothing going for it besides the refresh rate. If you're on a budget you can find 24" 1080p monitors with 144-165hz refresh rates for $150 or under and unless you're playing shooters at a near-professional level you won't notice any difference. 
 
The Asus is 1080p at 27" so the pixel density is going to be shit. Again this is a monitor for people who just want refresh rate and don't care how stuff actually looks. For $130 more than the Acer all you get is 280hz over 240, see my comments about 240hz refresh rate in the first paragraph. This is not good value for the money at all IMO. 
 
The Samsung steps up to 1440p which is at least a non-pleb resolution, although at over 30 inches pixel density is still not going to be great. Can your hardware even run the games you play at 1440p 240fps? It at least offers features to justify the higher price tag like QLED and a USB hub. 
 
If you play a wide variety of game genres then the sweet spot for you, as it is for most people these days, is probably a 27", 1440p, 144-165hz display in the $300-400 range. There's lots of good options available. 
 
 
 
 
 
 
 

I swear I did read your sentence 5 times and I saw "porno" in it 5 times

I'm going to go out on a limb and assume old/tight m-itx case with poor/no airflow, thus wanting a lower TDP.

Why would you want to do that?
Yes, it will perform worse on ECO mode.

If the difference between the 6800 and 6800XT is only 100 dollars, then I'd go with the 6800XT. After all, if you keep the card for a few years, you probably won't miss that 100 dollars. 

I had a 3070 and to be honest I wasn’t that impressed with regards to ray tracing performance. In my opinion the performance hit was just too great (I play at 1440p 144Hz). 
By an incredible stroke of luck a used RX 6800 came up on Amazon at an incredible price (it was actually brand new in box). So I sold my 3070 and kept the 6800. 
Having had both cards, my opinion is that the 6800 is the better card if you are not bothered about ray tracing. The 16 GB of VRAM is also something to consider as is smart access memory, especially if you are going for an all AMD build.

Thank you all guys. Guess i am going with the 6800!

Interesting... In which games is the RX 6800 slower than a RTX 3070? According to pretty much all reviews the RTX 6800 beats the RTX 3070 hands down, especially at resolution that is not 4K.  
 

 
Regarding the question of the OP, for that price RX 6800 all the way. 
 

Do you plan on Ray Tracing? If no, 6800.
If yes, price to performance, 3060 TI. If you want ~~10% better for $130, 3070.

Out of those two I would choose the G7 unless you're going to calibrate the monitors yourself as the Dell has horrible factory calibration.
https://www.rtings.com/monitor/reviews/dell/s2721dgf
https://www.rtings.com/monitor/reviews/samsung/odyssey-g7
 
But there are other good options around the $500 range, take a look at these also.
https://www.rtings.com/monitor/reviews/lenovo/legion-y27q-20
https://www.rtings.com/monitor/reviews/lg/27gl850-b
https://www.rtings.com/monitor/reviews/asus/tuf-vg27aq
https://www.rtings.com/monitor/reviews/gigabyte/aorus-fi27q

If you value the aesthetics, the Levante 240 is a decent option and far from a bad deal. Using it as a top exhaust is a good idea and the extra cooling does allow for a bit more performance especially with oc'ing. 

You mentioned that a Hyper 212 RGB BE was already ordered here and is fine:
If you're after value, getting a cooler that's several times more expensive isn't the way to do it since it doesn't make a huge difference in performance.

Recently I tried the SNOWMAN coolers on AliExpress (after seeing several YouTubers review theirs). I bought 3. They are great. I personally wouldn't consider any overpriced localy-available 'big name' brand after using these.
 
If you can wait, they are worth trying! There are 4-heatpipe designs with quiet 120mm fans. There are 6-heatpipe designs too. Prices are around 20 USD.
 
 
 

My 8086k can manage 4.7 all core with temps in the mid 60s in a synthetic benchmark. Mind you, I live in the Midwest so I believe that's a bit farther from the equator than you but I don't imagine the temps being unacceptable for you.

Then is the GAMMAX 500 only slightly more than the 4 heat pipe coolermaster cooler?

As it'll be fine for a Ryzen 8 core.

https://br.pcpartpicker.com/product/WskgXL/gamemax-gamma-500-argb-5118-cfm-cpu-cooler-gamma-500-argb#

Currently using the hyper 212 black to overclock my i7 CPU. For a mild OC, it's definitely adequate

For $98, that AIO is a pretty great deal. The MSRP is supposed to be $150 USD. It's not the best AIO out there, and I've heard some reviews saying it can get a bit loud, but it performs at the same level as H150i Pro, which is significantly more expensive. 

Definitely the AIO, especially if you're wanting to overclock the 5800x.