A couple of questions:

• Does the <1400€ target budget need to include a screen, keyboard, mouse, speakers, etc? If so, you'll probably want to set aside 3-400€ for those.
• Do you think you'll prefer smoother gameplay (high refresh rate) or better graphics? (Higher resolution, ray tracing.)

As others have said, https://www.logicalincrements.com/ and https://pcpartpicker.com/ are both great sites for helping you pick out what parts to get. I also wanted to mention that logical increments has guides for screens, keyboards, mice, etc.