What's the highest megapixel camera (other than the Canon 5DS) around?

I have the Nikon D5300, and Fujifilm x-a1, they're both great, but I'm looking to invest in a higher megapixel camera. Can anybody here give me some suggestions?

A colleague of mine has a Phase One XF camera with an 80 mp sensor

The Nikon D800/D800e and D810 and D810a each have 36 mp sensors

In the real world, a 12 mp sensored camera is plenty when shooting sports or other subjects destined for a magazine.

It is rare any more that we ever get a double truck (10-1/2x15 inches) with one of our images. If we do, the 12 mp camera like a Nikon D3s is certainly up to the job. What is more important is how well the sensor performs in low light (high (ISO)

Here are two links.

One to a landscape shot using a 36 mp camera and the other shot using a Phase One 80 mp camera

NOTE: My Nikon D800e was purchased used (low mileage) for $1600.
The Phase One costs just under $54,000 with the 80 mp back and 80 mm f/2.8 lens

You have to ask yourself how much you are willing to pay for more pixels. If you jump ship to a different brand camera, you need to factor in the cost of replacing any lenses you currently have. The D800/D800e can use any DX lenses you happen to have

There was a 250mp camera in the news recently. Military grade though…

http://www.canon.com/news/2015/sep07e.html

As seen here
http://www.cameralabs.com/reviews/Canon_EOS_5DS_R/Canon_EOS_5DSr_vs_Sony_A7r_II_quality.shtml
Cameralabs was able to obtain some sharp images on very high resolution sensors viewed at 100%. But that sharpness doesn't serve itself up easily.
"Both cameras were also set to their base sensitivity of 100 ISO and metered the same exposure. I focused them using magnified Live View to avoid front or rear focusing issues, and used mirror-lockup on the 5DSr to avoid vibrations."

For non-military use, it's the Hasselblad H5D-200c at only $45,000 http://www.bhphotovideo.com/...yes&sts=ps

However, you can go far beyond a mere 200MP by using a Gigipan and stitching images together which will only set you back about $1,000

http://www.roundshot.com/xml_1/internet/en/application/d77/d122/f123.cfm

Canon's 50-megapixel EOS 5DS is the highest-resolution full-frame DSLR ever

If you thought the megapixel wars were over, think again: Canon's latest DSLRs cram just over 50 of them into a full-frame sensor. The EOS 5DS and 5DS R variant - which omits the antialiasing filter for better sharpness at the potential expense of moiré patterns on fine textures - have so much resolution that you'll get 19-megapixel images even if you shoot in crop mode with lenses designed for APS-C sensors. They're the highest-resolution full-frame DSLRs ever.

Other specs include shooting at 5 frames-per-second, 61-point autofocus, dual Digic 6 processors, 3.2-inch 1-million-dot LCDs, 1080p video, a mirror vibration control system to combat camera shake, and viewfinders with 0.71x magnification and 100 percent coverage. Both the 5DS and 5DS R will be available this June; pricing information isn't yet available.

Canon is also introducing a new 11-24mm f/4 L lens, which it says is the widest-angle rectilinear zoom lens in the world. (Rectilinear means that the glass has been optically corrected so that straight lines are rendered free of distortion even at extremely wide angles; fisheye lenses can be wider, for example, but give you severe distortion.)

At the other end of the scale to the 5DS, Canon is also releasing new models in its popular line of entry-level DSLRs. The Rebel T6i, follow-up to the Rebel T5i, is a pretty standard DSLR that should match up to the mirrorless EOS M3 in most respects; it uses the same 24-megapixel APS-C sensor and has added Wi-Fi connectivity. Another model, the T6s, shuffles the layout around to make room for an extra dial and top-mounted monochrome LCD, making it closer to a high-end DSLR in operation. Both cameras will be available in April; the T6i costs $649 body-only, and the T6s is $100 more.

For now, for general consumer, the Phase One IQ-180 has 80 MP.

Higher than that - it's not general sensor we know any more.
Hasselblad deploy muli-shot mechanism and combine 6 shots to 1 picture to yield 200 MP.

Higher than Phase-one is "line scanner" sensor type.
Better Light Co. Offers many camera that capable from 200 MP to 2800 MP.

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Canon is currently developing the 250 MP.
The prototype one is 120 MP that offers 21 megabyte jpeg! Schedule to be released around end of next year.