I use nothing but Dicor on my 32' roof on a '97 trailer. I do a roof check in the spring before the trailer hits the road. Most of the sealant up there is still OEM. The first Dicor I used was when the trailer was 5 years old and the skylite cracked. I had too replace it while we were camped 480 miles from home.
Most folks use too much (thick) roof sealant which may crack in a couple of years. We see lots of OEM jobs that looks like that.
However sealant cracks may not mean it can leak.
1st line of defence against water intrusion is is the grey butyl tape. If that job was done right it won't leak.
2nd line of defence is a good sealant properly applied over the screws and around the edges like the brands mentioned.
There is no sealant or tape that is maintenance free.
