Rule

Idk what you're on about I love the buggy/hovercraft segments

They're just kinda boring IMO, only driving down narrow corridors until you reach some roadblock where you repeatedly just get out -> do some shooting -> undo the roadblock -> make your way back to the vehicle -> drive down narrow corridor again -> repeat.

Halo at least feels mechanically different (the most common vehicle, the Warthog, is very physics-based so it feels much different than just walking, whereas the HL2 vehicles just kinda feel like moving fast) and usually used in conjunction with larger more open level design to make the vehicles feel more useful instead of strictly necessary, or in levels that give you heavy vehicles like tanks they are useful in taking out a large amount of enemy vehicles so it functions like a powerup and feels rewarding. Also you can get marines to ride with you and use the turret (or even have them drive you and you get to use the turret) so it shakes up the gameplay more.
- I feel like for HL2, the vibe was more important than the gameplay for those segments. While you aren't technically doing anything too interesting, I still felt cool driving around.
Is there a multiplayer racing mod for hl2? I feel like that would be fun
- There's a racing mode in Jabroni Brawl Episode 3, a very silly sourcemod you can get from the steam store (afaik only requires HL2E2 to install), but there are only a few maps for it
- Seems like there are a bunch of Garry's Mod maps for racing, idk if they include racing mechanics like laps and everything, but it seems like you could boot these up with a friend and just keep track of who is winning.
  
  https://steamcommunity.com/sharedfiles/filedetails/?id=297300168

Personally highway 17 is one of my favorite chapters of HL2 so I can't necessarily agree But I do think the warthog is much more fun

honestly I think Route Kanal is my favorite because it scratches that itch of exploring old forgotten areas, climbing around cavernous drain pipes and stuff allows for more creative architecture.

Was it only me that got like serious headache especially in those levels? Kinda nauseating.
Maybe it was because of my potato pc idk

A low FPS could maybe give you a kind of motion sickness or something? Plus the droning of the engine is kinda annoying, I never had that problem but I can totally see it.
- What is droning?

The vehicle levels in halo were better, but at least I could drive the airboat for longer than 30 seconds without flipping it.

Skill issue :D

I'm the weird guy who loves Water Hazard. Easily my favourite part of the game. Run the combine over with an airboat, break the scaffolds they are standing on, look at the goofy ragdolls. And I'm a bitch for sunsets.

"Follow Freeman" is the worst imo. I remember getting horribly lost there when I played HL2 as a kid. Same issue with Ravenholm - even when I play it now, but the vibe carries it.

In Halo the loading is seamless but in hlf2 its so annoying

That's true, but Halo also has actual level loading screens that take a few seconds, I think the in-game "Loading..." message is about entities/scripts or something.