I want discs that are not going to rust
unrealistic and completely unnecessary. Doesn't affect ride quality one bit.
I want it to run smoother and quieter
- buy quiet tires and make sure wheels are aligned and balanced
- check the engine mounts
- make sure there's no play in suspension, steering, axles, bearings etc.
Can you recommend what brand of parts I should use?
Depends on the particular part. A lot of what VW makes is garbage.
I now have 200,000km
you're approaching the end of life for a VW. Things will start falling apart if they haven't already, because they're cheaply made. As Scotty says, they're rolling piles of junk (this I know from experience), and money pits as they age, so I wouldn't dump too much money into it. Save up for a Toyota instead.
If your struts are worn or leaking most of us here recommend KYB. Avoid cheap Chinese quick struts. Unless suspension parts are worn/loose there is no reason to replace them.