I cannot tell you know I work for, but we did some testing of a few products at work. Testing involved several aspects. Ability to creep (two steel plates separated by thin shims). Ability to displace water. Salt spray. How easily the product washed off, etc.
We found the Krown to be far superior to the other products.
Krown T32. This product is red/pink in colour. It is a bit thinner that T40 and is usually used by most outlets.
Krown T40. This product is tan/honey coloured. It is a bit thicker than T32, but still flows very well. I prefer T40, especially for the underside of the vehicle. I also use it inside all the panels. This weekend, the temperature was about 5C and the T40 began seeping out of all the joints again.
You can also specify the above Krown products with Krown Tack.
RustCheck didn't do as well as the Krown. We also tested some other products...can't remember which (another lab at work did the testing).
I chose to use Krown T40 for my Honda CR-V. I buy it by the 20 liter pail and use my own compressor and applicator to apply it.
I also do not drill any holes. I remove my interior door trim panels, etc. Most owners will not go to this extent, but there are a few things you can do to avoid having them drill holes. Rocker panels often have rubber plugs under the car that can be removed for rustproofing. The same applies to the B pillar where the door electrics enter through a rubber grommet; pull it off while spraying. Same goes for the front hoods and rear trunk lids or hatches.