Yes, the rubber ones are better. The Part Number for the upgrade kit is 026 198 025 C
You can get it much cheaper through
German Auto Parts. Leaking might be caused buy the stamped steel valve cover warping or bending. Get hold of an aluminum valve cover from a Corrado G60. The aluminum VC plus the rubber gasket will cure VC oil leaks permanently.
Oh, and check the splash shield under the VC, if it's broken or missing, replace it. Part # is 026 103 547 and is
available for $5-$7