Like:
Platforming
Non-Euclidean weirdness
Tech bases
Withholding the Super Shotgun for as long as possible
Puzzle vibes like The Given, Moonlight, The Grove
Small scale encounters
Cool SR50 skips
Atmospheric music
Strong color contrast
Dislike:
Hell
Rocket launcher-centered encounters
Rocket jumping anywhere
Custom monsters
Slow elevators
Levels that start with pressing a switch (no idea why I hate this)
Puzzles with arch-vile jumping
Damaging floors without any radsuits (obv besides sector 11)