Depends on what you want in a game.

Since you haven't bothered to tell us what you're into, I'll just say that Halo 3 gives you much bang for your buck:

splitscreen, online splitscreen, co-op, and Forge - tons of replayability.

KZ2 was great at first, but the game feels like it lacks depth. I'd probably be playin it more if was as tactical as GG wanted it to be. Unfortunetely, they let a few certain classes ruin that part....

If you think KZ2 isn't different enough from the rest of the FPS genre then I don't see how Halo 3 is.

KZ2's multiplayer is constantly changing from mission to mission, you unlock classes as you gather experience, and clans are integrated directly into the game.  Tell me another FPS that does that.

I think what people are trying to say is that KZ2 has no innovation at all and despite all the PR talk, it didn't live up to a lot of the people's expectations after almost 5 years in the making and 60m dollars, it brought nothing new on the table as far as game play goes. It is in noway a bad game as I've said many times myself, but it was returned non the less.

what gameplay aspect did Halo 3 innovate in exactly?

I think you haven't played Kilzone 2, dam i don't think you have even played a ps3 too. You are a fanboy and your profile prove that. dam even having Souja boy in you profile is simbol of bad taste.

@TorillianHalo 3 is generic but its not 100% generic like most shooters these days (COD Copy cats),R2 is better than Halo 3 IMO,If i was you OP i would get R2 or L4D but your prbly gonna go with KZ2.

well you wanted to know why people said it was generic, I feel the exact same way about halo3(even though dev time and money spent was much lower) myself since I'm a PC FPS person so I don't like that game either, so if you read my first post in this thread, I said to get a PC lol >.>;

i think you need to point out who you are talking to if it's a direct response to somebody

I'm sorry Torillian, but I don't see this thread going anywhere except fanboys fighting over two great games they haven't played.

Btw, I have played Killzone2, and its truly the most unique experience i have playing a FPS, its just so different, fun and weird at the same time.

Forge. I haven't even played the damn game but I've seen what that can do. It's amazing.

Having played tons of shooters on PC/consoles, the two bolded parts are probably what stand out the most compared to the others. 

As for the classes: