i have had both. i like the fact that when I spread jam on a piece of bread, when i am have a piece of toast in the morning it doesn't fall off the bread into the plate. it stay there. i get to enjoy the taste. i do like jelly but prefer jam.
I like both, although I have jam more often. I really love raspberry jam, but usually end up buying strawberry, for my daughter, which is good too. Actually, your discussion has caused me to crave jelly, and grape and apple are my favourites.