I have used most all of them they all have their pros and cons.
Magliner- very durable holds a lot of stuff/ cant fold it and takes up a lot of vehicle space even broken down.
Multi-Cart/Rocking-Roller- Same cart for those who don't know. Good build, extends 3 to 6ft so can hold a lot of production gear. it is my personal cart and I routinely put over 500 lbs of kit on it. That said it is too big to use as a primary cart if you are a local news shooter and only hauling a camera and tripod with perhaps one light.
Kart-A-Bag- I used to use them when I was still shooting local stuff. It is perhaps the best bag cart out there It is solidly built nd durable. It will easily hold a camera plus run-bag and heavy tripod. If you look at the picture there is a second set of wheels on the handle side that fold down and can be used to keep the whole thing at a 45 degree angle for easy pulling. If you a local news or sports guy and don't own one, spend the money now. The only con I ever found was the small payload which only really started to matter when I went into network and EFP work.
The foldable wagon things. (sorry don't know what else to call them) They are quick and easily sourced. I know a couple of guys that use them, I don't. The biggest pro that I see is that the bed is all self contained so if you throw a loose water or cable in and it won't end up dragging on the ground. It also seems to pack up small. The downside that I so see is that like the ez-up tents it is essentially a consumable which wont last for years and years like the other options above.