Big, beautiful and wonderful doggies, for sure.
However, any dog can bite or be trained to be aggressive. Although pit bulls and rotties account for the most deaths in connection with dog bites/attacks… over 30 different breeds have been documented as deing involved in bites/attacks in the US… and pits and rotties do not top the list in terms of frequency of bites/attacks. I think, though I cannot find a link, that labs account for more bites than do pits! 
I’ll keep looking…
Actually, unless I am mistaken, mutts are responsible for the highest number of bites/attacks and dogs left chained but unsupervised account for more bites/attacks than do dogs chained or unchained but supervised.