For me it’s either Splinter Cell Chaos Theory (lot of different ways to play through, getting stealth rating’s to 100% and just very satisfying game) or Uncharted 2 (linear but amazing campaign, replay value mainly just experiencing those wonderful moments again and again, but also looking for treasures and different difficulty settings).
Doom Eternal, the Resident Evil 2 and 3 remakes, and Half-Life 2.