I've never even seen Braveheart aside from a few short scenes here and there. I just have no desire to watch it. I probably should at least once just so I can say I saw it, but I jut don't think I could sit through it.
Kingdom of Heaven, on the other hand, I liked as a movie, and the costumes were [with a few notable exceptions] more or less period and rather nice-looking for a Hollywood production (meaning not overly fantasized). As a historical reference...not so much, but as an entertaining movie, yes. I think it's enjoyable, as long as you know fact from fiction. Unfortunately, a lot of people don't, nor do they care to look into it any deeper than what's on the screen.
How they portray the Templars is probably my biggest beef. These days, it seems like it's "cool" to portray the Templars as bad guys (see also: Assassin's Creed). Then again, considering how the Order ended, I guess it was cool to pick on them back then, too. It really is a shame.
Between Kingdom of Heaven and Arn: The Knight Templar, I'd have to say I like Arn more. To me, it was just a better storyline; it wasn't your typical Hollywoodized "Attractive hero rides off into the sunset with attractive leading lady ad they live happily ever after". I found that Arn's ending left me more satisfied with the story than KoH, but maybe that's just me. I'm sure a lot of people don't feel the same way about it.