Getting out the popcorn. This is going to be good.
All seriousness aside (or something like that), this has always been a contentious topic on RV forums. There are many good products out there (as well as some bad ones), some traditionally used by the RV market, some by the stick & bricks market, and some by the marine market. Some people will swear by certain products while others will swear at the same products.
I personally eschew silicone products. Once upon a time, they were the best thing since hot & cold running water but they have long since been superseded by other products, such as the polyurethanes (although silicones are still the best for bonding glass to glass). A serious problem with silicones is nothing will stick over them, including silicones. When they fail, removing every last trace of the silicone is a chore but necessary to ensure whatever is used to replace the caulk will stick.
Dicor self leveling sealant has been a favorite for sealing seams on roofs but requires frequent inspection since it will eventually dry out and crack. Many people like to use Eternabond tapes are popular for both repairs and for proactively sealing seams before they can leak. The tapes are long lasting. The major downsides are they are not the most attractive thing on Earth (which shouldn’t matter if on a roof) and they are a bear to remove if you should ever need to. Eternabond also makes a double sided tape that can be used to seal windows, furnaces, water heaters, etc. to walls but, again, it will be pretty much impossible to remove those components without damage if you ever need to. It will seal pretty much forever, however.
Putty tape and butyl tape are what have traditionally been used to seal windows, furnaces, water heaters, etc. Butyl tape is superior to the older putty tape but, unfortunately, some manufacturers have been calling their putty tape butyl tape.
Many marine products, such as 3M 4000UV, 4400, and 5200 have been migrating over to the RV market. 3M 4400UV can be used in place of a caulk such as Dicor but sets up fast so is difficult to use. 4400 and 5200 are bedding sealants and should be used in place putty or butyl tape. 4400 is UV resistant and easier to remove if necessary whereas 5200 is not UV resistant and is almost impossible to remove without doing damage.