In the end I guess it comes down to personal taste, but for what it's worth I prefer Braveheart - although both have inaccuracies and flaws.

In the case of Braveheart the implied 'romance' between William Wallace and Isabella of France is one of the most glaring, considering WW was dead before the Prince of Wales, Edward II married Isabella! She did betray him eventually though and almost certainly conspired in his murder in Berkley Castle.

Gladiator is sort of watchable, mostly for its entertainment value only.

I suppose you could pick holes in the historical accuracy of the 2004 King Arthur offering with Clive Owen and company too, but I really enjoyed this movie regardless.