I don`t have a HL2 favorite chapter Blast Pit in Half Life 1
In HL1, I loved “We’ve got hostiles!”, because of the first encounters with the military - I very much liked fighting the HECU marines. Those were my favourite parts of the game.
In HL2, Ravenholm is among my favourites, because I love to kill headcrab zombies with physics props and fire. Also, Father Grigory is one insane badass motherfucker. I also loved “Nova Prospekt”, because of the gloomy atmosphere that old prison complex had. And, of course, I loved dicking around with antlions, using them as distraction against enemies.
Episode 1: The part in the hospital when Alyx picks up a shotgun and extreme zombie massacre ensues.
Episode 2: This Vortal Coil. Although I have missed 13 (!) grubs, despite searching every room and tunnel in every direction. I have no idea where those 13 little buggers might be. But Griggs and Sheckley are a hilarious team, and the vort who escorts you into the mines is the coolest companion in the whole series - apart from Alyx, of course. This is probably my most favourite part in the whole series. I keep playing it over and over again (and not only because I want that bug achievement), because I like defending Alyx & the vort from antlions. It’s easy as hell, but for me, never gets old. A little bit like Moorhuhn.
“Sheckley.”
“What?”
Sheckley!"
“What?!”
…
“Forget it…” 
Blue Shift: The part where you escort Dr Rosenberg to the old test lab and help to activate the teleporting device. I like escorting npcs, I guess.
Opposing Force: The Part with all the observation areas and aliens examined in laboratories. Also: The areas where you first encounter Black Ops.
Foxtrot Uniform
We Are Not Alone
This Vortal Coil
Surface Tension
Lowlife
Highway 17
Residue Processing
The part in Blue Shift when you’re looking for Rosenberg.
Captive Freight
The Package
Questionable Ethics
Follow Freeman
Undue Alarm
Lowlife
This Vortal Coil
I’m not really very good with the names of the chapters but I’ll try.
We’ve Got Hostiles
Forget About Freeman
Anticitizen One
Our Benefactors
Dark Energy
Urban Flight
Our Mutual Fiend
Our Mutual Fiend, of course.
1: Unforeseen Consequences.
2: We Don’t Go to Ravenholm.
3: Every other chapter.
All of it, except our benefactors and maybe anything involving race x or a worm
Half-Life 2
We Don’t Go To Ravenholm
Half-Life 2: Episode 1
Low Life
Half-Life 2: Episode 2
White Forest
T-Minus One
good johnworfin.agreed
Most of them were posted already. However, the chapter in Half Life: Uplink is maybe the most intense and fun… or that I just haven’t played it since like 12 years heh.
Can’t believe I regged just for this. :facepalm:
of course the chapters where I drive the vehicles: Water Hazard; Highway 17; Riding Shotgun (for regular gameplay)
Follow Freeman!
and
Our Mutual Fiend
for boss combat.
Water Hazard+Highway17
[COLOR=‘Red’]Merging with the existing threads.
Half-life first chapter and ending.Half-life 2 first chapter. Episode one ending. Episode two T-minus one. Fighting is bad.
I’ve said it before and I’ll say it again, Blast Pit 
Half-Life: The alien grunt factory in interloper, I enjoyed seeing vorts doing something other than zapping
Opforce: Seeing Freeman teleport to xen and causing a temporal paradox
Blushft: Thinking I’m safe in the truck only to have the top blown off it
Decay: Fighting through the destroyed hazard course
HL2: We don’t go to Ravenholm (very good atmosphere) and Breen’s talks in the citadel
Ep1: The ending
Ep2: The vorts healing sequence and the following Gman scene
Portal: GLaDOS’ quotes in the final battle
I have to agree on that one.
Follow Freeman always seemed to be my favorite (in HL2 at least) for some reason. I’m not sure why. Maybe it’s something to do with the satisfaction of taking down those Striders… or something. 
My favorite level so far in any HL game though is probably Surface Tension. HGrunts showing off their stuff.
In HL² there was this scene where a pod hits a smokestack and it crushes down into the river you were driving in. I didn’t really expect that had an “wat”-moment.