I thought Broken Sword 3 was a lot better than The Longest Journey. TLJ was a little too long-winded for me, I didn't find the dialogue or the story very interesting. However, BS3 was a little short, and lacking in the puzzle-area. Both are good though.
If you're looking for a more puzzling game, with puzzles, choose TLJ. If you're looking for an exciting story and "snappy" dialogue, get Broken Sword 3. Unless you absolutely despise crate-puzzles.