Lots of good products out there. Everyone has their preference. They all take about the same amount of labour to use so you might as well spend the extra $ & get a good wax/sealant that will last. The multi purpose cleaner wax are not as durable but you need to start with a clean surface with the wax/sealants.
My preference? The Mequires Flagship wax. Expensive but only used once a year on sides. Twice a year on front cap. The trailer looks new but is stored indoors for 7 months of the year.