Is Canon 7d mark 2 a better choice than nikon d7200 for portrait photography?

The Canon (or even a Pentax) won't do anything the Nikon can't.

Basically, the camera/lens isn't the problem here.

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Possibly the lens is the problem, though Tamron is one of the top three independent lens makers, and has a good reputation.

Frankly, you have an excellent camera, and I doubt that changing brand will satisfy you in terms of quality - both Canon and Nikon are excellent.

You should get some guidance face-to-face from somebody who knows about such matters, and who can look at your pics and find out where the problem is. Is your camera properly set up for Resolution and Quality?

Indeed, unless you are in stratospheric areas in your quality demands, you should get good or excellent results from crop-frame DSLRs. Crop-frame cameras from good brands have so much quality available that you will very seldom come near to pushing them to their limits.

So, get some local advice before spending quite a lot of money.

All dSLRs are basically the same. You will get the same picture no matter what dSLR you use. Picture quality depends mostly on your skill.

Getting a more expensive camera will not improve your shots. It will only make shooting easier, if you know what you're doing. If not, you at least get more bragging rights.

Without seeing the "horrible" shots, it's not possible to really determine what's the problem here. Based on the body/lens combo, the bad image quality is almost certainly user error.

The 7d II will be significantly better for sports and wildlife than the D7200, but when taking a shot of a person standing still with a f/2.8 zoom, you won't notice much of a difference at all.

Not happy with portraits? Your camera is a good as any other, just buy a 3-point lighting system and learn techniques. (Focus on the eyes, you and the model need teamwork to get good results.)

Sports? The 7D Mk 2 might make it easier with its 10fps rather than 6fps. But if you anticipate the sport well that may not be necessary.

https://photographylife.com/nikon-d7200-vs-canon-7...

It is a poor workman who blames his tools.

If you can't take a good portrait with a D7200 then the problem is not the camera and replacing it will not help one iota.

Spend your money on some lessons to improve your skills.

The Canon (or even a Pentax) won't do anything the Nikon can't.

Basically, the camera/lens isn't the problem here.

Portrait photography is all about lighting and photographer skill. If you give both those cameras (with equivalent lenses) to a competent portrait photographer you will see absolutely no difference in the final image.