I am planning to use an ARM to mount the monitors. Dont know if they support curved design or not.
Firstly I tought about flat monitors becouse of arm. Dunno if it will work with curved.
Curved sounds better

Yeah curved work no problem. When going curved triple monitor you want to keep the curve to a minimum, 1800 curve radius is ideal.

What's your overall budget for monitors? Def need that for this one lol

well, up to 500 usd per monitor.
Overall max 1500 usd for 3 G-sync compatible setup if possible.

Couple options that are reflective of price you're seeking;

1. Dell S2722DGM (27" - 1440p - 165hz - VA Panel) $279.99 USD
2. MSI Optix G27CQ4 (27" - 1440p - 165hz - VA Panel) $255.55 USD

1500R curve, seems hard to find anything around 1800R curve in a 27" panel but this will still look great

I would go Dell personally. Dell and LG are the largest panel produces in the world, although Dell has bad customer service, their monitors are very good.

I would just keep them all the same for the price too, then it's seamless and looks crisp.

GL