You read all the negative comments on forums because that's where everyone turns to when they have a problem. If there's nothing wrong with the product you will never hear about it because the owner is out using it and too busy to write a positive review.
I had a 2011 Yamaha Rhino 700. It was great for riding around the mountains and trails, but when it came to hauling and towing it falls very short of the capabilities of the Ranger. If you ever plan on making your UTV road legal, stay away from the Rhino because the rear axle is fully locked without a way to disengage it at all. So you'll end up tearing up tires and the rear differential and CV axles will end up failing. The ranger has a turf mode, or a differential lock disconnect mode so you can run with an open rear differential not only on your lawn but also on pavement which takes the stress off your drive train components.
The Rhino has a bed capacity of 400lbs, the Ranger is 1,000lbs.
The Rhino has a towing capacity of 1200lbs, the Ranger is 2,000lbs (yes 1 ton towing).
The positive on the rhino is it comes with a centrifugal one way wet clutch system in the transmission allowing you to have engine braking in both 2WD and 4WD. No freewheeling down hills like the rangers love to do.
The Rhino also has selectable 2WD, limited slip 4WD, and fully locked 4WD. When you engage 4WD its in 4WD unlike the Ranger where you flip the switch to 4WD and the electronics in the machine decide when you need 4WD and when you don't. You have no control over the 4WD system in the Ranger, you have full control on a Rhino.
I loved my Rhino until I started hauling firewood and that's where I realized it wasn't a big enough machine. I'm looking into a Ranger HD800 here soon. The HD version has engine braking and self leveling rear suspension to keep your ground clearance close to an unloaded machine even when fully loaded. The Rhino doesn't have that feature so when you are pushing your load capacity limits or towing you will lose practically all useful ground clearance and will hang up the underside of the machine a lot.
I like the Yamaha Rhino but after being able to use a neighbor's Polaris Ranger XP800 for a day I really like the Ranger's features, ground clearance, stability, and load ratings a lot better.
The Rhino will destroy your lawn if you try to use it for utility use and make any tight turns because you cannot unlock the rear axle. The Ranger gives you a selectable Turf Mode, locked rear differential, and 4WD mode with the push of a switch.
I'm not sure how the front gearing is in the rangers, but the Rhino had a fully locking front differential, the ranger I think is only limited slip, but everyone who has a ranger that I've talked to says they have never had any problems not having the fully locked front differential on their ranger.
Seems like accessories are more plentiful and a bit cheaper for the Rangers than for the Rhino's too.
I have never been around or operated the Honda Big Red UTV, so I can't even begin to comment on one. I've never even seen anyone where I live that owns one either so they must not be that great of a machine. Where I live its Polaris Country, probably mainly due to the horrible Yamaha Dealer in my area.