I have the MC sportgate and I love it. I can go with any bumper at any time. Sure I am limited to my tire size because of the weight limit being 150lbs but at this point in time I don't plan on ever running more than a 35" tire.
I have a gate mounted carrier. It's simple and functional and integrates well into the door release. The downsides being the weight limit (usually 37" tire max) and limited number of accessory mounting points. My carrier can hold one rotopax or a hilift jack, but that's about it. Typically less expensive than a bumper carrier since you're not usually buying a bumper with the setup.
Most bumper carriers will hold more weight. Some will even have a number of add on mounting points for accessories. Potentially more expensive if you have to buy the bumper with the setup. But overall you're getting more weight capacity and probably more options for carrying more stuff.
Like most everything Jeep related, it just depends on budget, what you do with your Jeep, and where your build will take you to determine the best option.
Building off El Sanchimoto and gingerempire's responses, it depends on which size tires and your vision for your Jeep. With my Dana 30 up front, I know that 35" is as big as I'll go, so I went with the hinge-replacement, tailgate mounted solution. If I were building a beast, though, there's no doubt I would pick a bumper mounted carrier – likely one with the extra steel protection back there.
In my recent research it depends on styling, weight, and future upgrades. gate mounted carriers will "lack" in style and weight capability but offer a larger selection of bumper options = style. They also open a few different avenues of future upgrades.
I can not speak on the bumper mounted carriers as i have the TF Gate carrier.
Price is also an issue. Gate mounted carriers are much less expensive than a bumper, carrier combo.