Hello,

I will start building my first rig and can't decide what GPU's to choose. I live in Eastern Europe and prices are pretty high. Budget about ~1,9k €

These are not final prices, will get 20% off.
9* INNO3D GeForce GTX 1060 3GB Compact 2 - 210€ - 1890€ and 6gb card price starts about 300€
7*  XFX Video Card AMD Radeon RX 470 8GB - 280€ - 1960€
7* ASUS Radeon EX RX570 O4G 4GB - 280€ - 1960€
6* SAPPHIRE VGA PCIE16 RX 580 Pulse 8GB  - 320€ - 1920€ or 4GB model? 290€ per GPU
4* ZOTAC GeForce GTX 1070 8GB - 480€ - 1920€
GTX 1080 is over 600€ per card

Or something else?

Other hardware:

INTEL Celeron G3930
BIOSTAR TB250-BTC+ only with 8 PCIe slots for GTX 1060s have to choose motherboard with 9 slots at least.
4GB DDR4
120GB SSD
Corsair RM1000X? Something else in ~170€ price range?

Is Chinese PCIe risers trustable?
https://www.aliexpress.com/item/3-in-1-4pin-molex-pci-e-riser-008-card-6pin-riser-sata-60cm-pcie-1x/32833403582.html?ws_ab_test=searchweb0_0,searchweb201602_5_5130011_10152_10065_10151_10344_10068_10345_10342_10343_51102_10340_10341_5000011_10541_10084_10083_10307_5080013_10303_10302_10539_10312_10059_10313_10314_10534_100031_10604_10603_10103_10605_10594_10596_5060011_10142_10107,searchweb201603_31,ppcSwitch_5&algo_expid=acb7a946-e07d-4f59-b7f6-e99bbebf3290-1&algo_pvid=acb7a946-e07d-4f59-b7f6-e99bbebf3290&rmStoreLevelAB=0

Best way to get ROI back and be future proof?