I prefer games like Red Orchestra Ost front & Darkest Hour; they're a bit dated (6-7 years old, UT2k4 engine) but it's 25v25 servers where you need to conserve ammo / grenades, no cross hairs (aim with iron sights) & generally 1-2 shot kills (no armour / health pack bollocks).
Quality ballistics (you need to anticipate moving targets, projectile trajectories dip, recoil etc)/ in-game physics taking in to account a slightly dated engine.
Should be dirt cheap on Steam.