I currently have a 2014 Suzuki Kingquad 750 a little over 400 miles so far and all is good. I had a 2005 before this one and it was bullet proof. Over 4000 miles of work on it from plowing 7 driveways every winter to hauling wood to feed our outdoor wood burner. I was not nice to it, but it always started and worked great. Fixed a cv shaft (boot tore and I never fixed) and 2 batteries. I would not hesitate to buy a Suzuki, Yamaha, or Honda.
I had a Zuki sport quad for a short time, but I am sure you’re not looking for one of those. They are fast little machines and are very reliable. The 400cc sport quad market used to be flooded by them, Arctic Cat (DVX) and Kawasaki (KFX) branded their own Zuki made machine for a while.