Tnx for your answer @Shizoru ! 
I have a laptop, Thinkpad X1 Extreme 1stGen, 15.6", UHD, i7 8750H, 32Go Ram, SSD, 2xUSB-C/Thunderbolt 3) on Win10. I also have an old laptop with 2-3 linux distro.
Iām working ~8-14 h/day in front of my laptop, 95% for coding, reading and writing. 5% YT, video, no gaming(just playing chess). However, I will probably do some streaming in the future and create some learning content. Quality has a price, and the budget will follow ! The Dell U3821DW seems quite similar to the LG, no ?
I remain open to any proposal and feedback from intensive Obsidian users! I buy very few things but I am looking for quality! Many thanks in advance for your help