As it happens, I think the alternate ending was one of the crappiest of the deleted scenes. Oh, the ship still sinks. But it was Cameron's rather clever use of the McGuffin diamond "bookends" which allowed him to continue the story past the point where the Titanic falls beneath the waves and have a second ending about the diamond.
Meh.
Me likes the original ending far more.
But here's one of the other deleted scenes that I'm rather fond of - - - after the ship sinks, Rose clammors on top of a piece of flotsam floating wood paneling. There's no room for Jack. Why does he stay there and lazily die instead of swimming about in search of some other flotsam floatage? Well, the deleted scene answers that quite nicely - as he is forced to defend Rose from a male passenger who wants to use the wood float to save himself, and Rose be damned. Jack warns the interloper off with threat of death, and thereafter it becomes a bit more believeable for Jack to hang out submersed in the 28-degree water next to high and dry Rose.