Please review the points below and vote. If their is a point I missed about either game message me and I will edit it in. Please post a message coinciding with your vote and why you chose that game. Nothing about popularity or expansions only original content.

Sin
-Realistic body damage
-NPC's
-3 type's of body armor
-Wide array of futuritic weapons and vehicles  
-Open GL compatable graphics
-Translucency (water and fog) & transparency mapped textures
-Storyline based on futuristic mad scientist
-Shooting range style training(arcade like)
-Hiearachical models with interpolated skeletal animations
-Mission-based levels
-Large, realistic environments
-Usable objects(drawer's, elevator's, lightswitches)
-Destroyable boxes and boards
-Destrution of walls through damage
-Cinematic movie sequences
-Total underwater levels(uwpass1,uwpass2)
-Mutant character change level
-Easter eggs and secrets
-Computer dos interface system
-Deactivation able turrets, cameras, bots
-Use weapon(like secondary fire)
-Inventory system
-Alternate levels routes and missable levels
-Usable cameras
-Stealth missions
-Existing on multiple sides of a plane
-Movie made off of the game
-1 expansion

Half-Life
-NPC's with healing and following capabilities
-Rechargable hazard suit
-Real-world, experimental, and alien-bodypart weapons
-Open GL semi-compatable graphics
-Translucent water
-Storyline based on alternate dimension alien invaders
-Hazard course training
-Skeletal Animation System
-Almost Seamless level transitions
-Usable objects(elevator's, lightswitches)
-Destroyable boxes and boards
-Event based destruction of wall
-In-game movies
-Deactivation able turrets
-Secondary fire
-3 expansions

As I said if there are more that you think needs to be added send me a message and I will add them in.

Well, I posted my opinion already in the other thread. IMO, Halflife´s way of story telling was a cornerstone for the FPS genre, but SiN had definietly the cooler characters and weapons (I absolutely hate HLs weaponry, bad mix of boring real-life guns and ugly alien garbage).

I overall liked SiNs style and design better then HLs. But the story was really... not so special, very predictable. Another thing that annyoed me sometimes in SiN was the cartoonish stuff. The bums in the subway ore the fat workers were just a bit silly. It s quite a time since I played SiN, but I remember that the enemies weren t as diverse as the enemies and monsters in HL. Some of the monsters in HL were really cool (the headcrabs or that giant tentacle beast, with the whole mission based arround killing the thing).

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Another thing that annyoed me sometimes in SiN was the cartoonish stuff. The bums in the subway ore the fat workers were just a bit silly.

SiN was able to bring a good humor to the game while playing and their are few games that have done that.

The basic concept for the headcrabs was derived from the Alien's facehugger and Quake's fiend.

The giant tentacle beast was really annoying and only got me irritated at the game.

Saying Half-Life was a cornerstone for FPS games is like saying Duke3D was a cornerstone for puberty suffering teenagers.

I can just repeat that the way how they told the story in HL was the one thing that made the game great.

The cool thing about the tentacle beast was that you had to use different parts of your environment to eventually kill the thing (activating oxygen in that part of the base, fuel in the other etc.). It gave you a deeper feeling of interactivity.

In SiN you had to deactivate a nuclear warhead by inputing the correct password.

That´s right, the interactive computer terminals were one of the strong points of SiN.

What I also liked was the level design in general. SiNs levels proof that you can build levels with a real world setting AND good gameplay. You just need creativity. The abandoned houses for example had a great ammount of interconnectivity and strong multi-level combat. The underwater mission was very refreshing as well, and the oil rig was another imaginative setting.

Post your reasons for your choosing of a game, just a vote won't cut it.

Half-Life had (and still has) gameplay I like. I'll just vote HL for that reason.  

While I still prefer Half-Life, I voted for SiN because it's not the crappy game many people (that probably never played the game) say it is.

Anyway, I have to make you some corrections:

- I don't know what kind of problems you had, but both games have the same level of OpenGL compatibility.
- SiN has no skeletal animation of any kind, only HL has. All the animations in SiN are premade, Quake 2 style. You can use almost any Q2-based model viewer to check this.
- SiN levels were not that large, not larger than Q2 levels at least.
- Destructions of walls in SiN were also event based or at least allowable (<- is there such a word?) in fixed places.

1) HL doesn't recomend any setting over 640x480 for OpenGL, any thing higher has gliches and most of the time does not display in full screen or full resolustion. I could go much higher than 640x480 in SiN. The original version no patches however seems to have no problems with compatability with graphics cards but with the updated high definitions graphics patch there are more then plenty of problems. But nobody compares the original HL where graphics are concerned anyway so I may as well exclude that out of my mind.
2) "Technical Key Features
-16-bit colored lighting in software and hardware mode (3DFX)
-Hiearachical models with interpolated skeletal animations
-Translucency (water and fog) & transparency mapped textures
-C++ DLL programming interface (for add-ons) " - features quote
3)Larger levels than HL though, HL had small short level that linked together Hexen style. SiN's underwater levels were pretty big though, but I'm not sure if they are bigger than Q2's levels though.
4) Weapon based damage destruction isn't completely a scripted event(although it can be argued as such). Sin had many of these while HL had none really.

Thanks for the thought though but none of those were completely in error. But if you can bring a valid point against what I have just said then I will alter my list. Thanks for the input though.