What is the best brand of dirtbike kawasaki,yamaha,suzuki,or honda?

All of them are good, each its own set of downfalls and set of traits that make it better than the others. But for the most part all of the brands you listed are equal. Look for a bike that best suits your needs, ignore the brand names, and just look at what the bike can do compared to what you need it to do. Also try and figure out how the bike was ridden/treated, if the previous owners beat the hell out of it, that bike is not going to be up to par with an identical bike that was babied. As for my personal preference on the best manufacture of dirt bikes, out of the japanese company's I ride yamaha. But I have noticed, in looking at family members bikes, european manufactures (KTM and Husky) seem to have a better build quality. They just look like they were put to gather with more care, and attention to detail.

well i have been using hondas all my life and my father went riding with some guys that had ktm's kawis and yamahas and they all broke down except for his 450 honda so you diside

Only a very good rider could say one of those is better than the other then to back it up with faster lap times. Any of the four Japanese factories make a good all round bike with some being better in one way but not so good in another. All of them will take what the average rider gives and they will have more to give than you ask for. Your question doesn't give the use you have for the bike(trail riding or motox) and doesn't give an engine capacity so we can only give general advise. Maybe, if you are planning on buying one, I would advise a 'sit and fit' to get a feel for each of the bikes, chances are the bike that feels best to you would be the bike you would be most comfortable on and ride the best. Unfortunately I have trolls that give me negative votes but apparently don't have the experience or IQ to answer questions themselves so I wonder how they can judge others answers. It doesn't worry me as I am only on this forum to give good advise to those that need it, trolls voting negative mean nothing, I'm not here for positive or negative votes, this Forum is about giving help and as a Top Contributor that answers the trolls.