@SergSlim Hi and welcome. The most important piece in determining the sound quality will be the speakers. If you can listen to any of those models in a store or friend's house, that would be preferred, as some personal preference does come in to play. Of the models listed, my preference would be the Polk R700 as it has been proven to be a good value for the money and excellent sounding. The Klipsch have a higher sensitivity, so they will play louder given the same power, but some people find the Klipsch horns a little bright (but that is a personal preference). Monitor Audio Silver has a good reputation but I have not personally heard any. The mid-range drivers tend to be on the small side which can be a concern. If you can get KEF as well, I would consider Polk and KEF.
Since your main speakers will be close to the TV, you can save some money by foregoing the centre speakers and using a "phantom centre" approach. With the speakers that close together, a centre speaker can interfere with the mains. Your rear speakers do not have to be the same brand but it can help with timbre matching. Polk Reserve also has some good bookshelf speakers for rear channel.
For ATMOS, I think a single pair slightly ahead of your seating area would suffice (like you have indicated in your diagram). Try and get a model with an angled baffle that aims the speaker at your seating area, if possible. If the budget is not big enough, you can pre-wire for the two ceiling speakers and add them latter.
The four AVR makes mentioned above are what most people use here, especially when starting out. We don't know what prices are like in Ukraine, though. Denon S series are less expensive for those on a budget. AVR-X2800H is a good starter if you want something a little better. The X3800H might get over your budget when you add all of the speakers in. You may get better pricing on comparable Yamaha and Onkyo AVRs but we would need to know your costs there. You will likely get 7.1.2 support in that price but having the two extra unused channels is ok (less draw on the power supply).
We would need to know what brand of subwoofer you can get. Avoid cheap Klipsch subs. They do not last. You need to move up to their higher models or look at SVS, REL, Rythmik and the like. A good subwoofer will take up a good part of your budget but will make a big difference in sound quality, especially for movie effects. The Polk R700 have very good bass for music, but if you like electronic music or pipe organ, which can go very deep, you will want a subwoofer that is rated down to 20Hz. (A subwoofer rated down to only 30Hz will add little to your main speakers.)
Provide what extra information you can and you will get some more recommendations from members.
