I have not used my Weber in a little while and I noticed there is a "Tea stain" on the bottom plate. Which of these two polishes would be better?
Having used both, I've not found a significant difference between the two. Maas may be a bit finer of an abrasive than the Flitz, so dependent upon how much material one needs to remove may steer you towards an appropriate coarseness of polish.
I used to use Simichrome with great results but found Maas to be cheaper per tube and just as effective. Never tried Flitz.
I use Noxon 7 with great results on my brass razors. It can be used on SS. Hmm is that "tea stain" rust? If not what else would it be...
I use a product put out by Stanley that actually is re-labeled Simichrome and it is less expensive. I found it on ebay and snatched up 3 tubes. Love the stuff.
It has to be from the blade that was left in it. It is on the polished section of the bottom plate so it looks like more of a patina.
If it's light blade rust, mere white toothpaste and a rag or q-tip may get it out. Sometimes it's worked for me, sometimes not, but it's worth a shot.
I have also had some good cleaning & polishing razor results with this: Mother's Mag & Aluminum polish
I have this in my resto arsenal as well. It is very mild and has some chemical in it that is excellent for removing staining & tarnish. Potentially your best option in this case actually.