My vote would be for the D7200... unless you need the faster 8 fps frame rate of the D7500 for some reason (sports?). Not that the D7200 is bad with 6 fps.

While Nikon intended the D7500 to replace the D7200, in some ways it's more of a downgrade... But either camera will be an upgrade from a D3300.

D7200 has 24MP sensor with about 1/2 stop wider dynamic range, slightly greater color depth, but slightly less usable high ISO than the 21MP D7500.

D7200 has dual memory card slots and a higher resolution (1.23 million dot) rear LCD. The D7500 has a single memory card slot and 922,000 dot rear LCD... However, the D7200's LCD is fixed, while the D7500's is articulated and is a Touch Screen.

D7200 can be fitted with the MB-D15 battery grip, which both adds a battery to double capacity, provides useful secondary controls for shooting with the camera held in vertical "portrait" orientation, and can help make for better balance if the camera is used with larger lenses. That battery grip also fits the D7100..... but it ]does not fit or work with D7500. In fact, for some reason Nikon designed the D7500 without necessary connectivity to work with ANY battery grip at all. No Nikon grip is being made for D7500. There are some 3rd party grips being made to fit it, but they do not provide the secondary controls like the MB-D15 (and 3rd party clones of it) did on D7200 and D7100. There is only a shutter release button and that requires and external cable to the camera, for connection.

Hand-in-hand with it's faster continuous shooting frame rate, the D7500 has a larger buffer. In combination with it's slightly lower resolution, the bigger buffer can accommodate nearly 3X as many images as the D7200 in a single burst, before the cameras need to pause to clear the buffer. Not that the D7200 is bad in this respect. In fact, it's ability to buffer 18 14-bit, lossless RAW files or up to 100 large/fine JPEGs is quite respectable. Still, that means in the RAW mode the D7200 can handle a 3 second burst at it's fastest 6 fps continuous shooting rate. In comparison, the D7500 is claimed to be able to handle a 9 second burst of those RAWs... 74 14-bit, lossless files.

D7500 also is capable of 4K video, while the D7200 is "limited" to HD.

Both cameras have built-in wireless, though the D7500's has Bluetooth, while the D7200 doesn't.

So, it's a mixed bag, between these two models. You just need to decide which feature set is better for your particular purposes.

Enough people still appreciate the D7200's assets that it's value has held up. There are few of them still available new, but when you do find one it will cost more than a new D7500. Used prices of the two are nearly the same, which is unusual for DSLRs. Usually the used market value of an older model plummets when an "new upgrade" is introduced. D7200 was intro'd in 2015, so is now about five years old. D7500 was rolled out three years ago, in 2017.

Here are some links to comparisons of the D7200 and D7500, for additional info:

https://cameradecision.com/compare/Nikon-D7200-vs-Nikon-D7500
https://www.dpreview.com/articles/3436918000/nikon-d7500-vs-d7200
https://www.apotelyt.com/compare-camera/nikon-d7200-vs-nikon-d7500

There are a number of other online comparisons of the two.

You also can compare either camera with your current D3300, where either would be a significant upgrade.

https://cameradecision.com/compare/Nikon-D7200-vs-Nikon-D3300
https://www.apotelyt.com/compare-camera/nikon-d7200-vs-nikon-d3300
https://cameradecision.com/compare/Nikon-D7500-vs-Nikon-D3300
https://www.apotelyt.com/compare-camera/nikon-d7500-vs-nikon-d3300

Note one key factor, the imaging sensor of your D3300 is very similar to that in the D7200. It is many other features of the cameras that set them apart. For example, the pentaprism viewfinders of the D7000-series cameras will be bigger and brighter than the penta-mirror viewfinder of your D3300. The D7000-series cameras have higher specification shutters, too... with a faster 1/8000 top speed, faster flash sync and higher durability rating. Looking at the above comparisons, you'll find much more.

D7100 (24MP, 2013) might be worth consideration too. I'm sure you'd be able to find a used one at lower cost than either D7200 or D7500. Use any of the above online tools to compare D7100 with any of the other models and your present camera... and search for additional resources, if you wish.

There have been rumors circulating for a while that Nikon will be reducing the number of DSLRs they offer, in favor of more Z-series mirrorless models. Supposedly they will be phasing out the D3000-series and D5000-series cameras, along with the D500 being the end of that line. If they actually follow through on this, it would leave the D7500 as their only DX/APS-C model (along with 3 or 4 FX/full frame DSLRs). However, I would note that there hasn't happened... There hasn't been any "culling of the herd" yet. The D780 update to the FX D750 has come about... and the D6 will be replacing the D5. But that's all we've seen... so far. Here are links to the articles from close to a year ago: https://nikonrumors.com/2019/07/02/rumored-list-of-nikon-dslr-cameras-that-will-not-be-replaced-with-a-new-dslr-model.aspx/ https://petapixel.com/2019/07/02/nikon-to-drop-1-3-of-its-dslr-lineup-in-shift-to-mirrorless-report/

I've had a query from an old colleague at work who is coming up to retirement and is looking at taking his photography more seriously.

He currently has a D500 and would like to consider a D7500 (an example of which he has found on a deal).

I'm a CANON user and could wade through the brochures but I've no practical experience with any NIKON with the exception of an old WP model.

Can you advise on whether this will be a good jump and will the lenses he had with his old D500 fit the newer model. I want to be sure there is not a CANON EFS / EF bayonet change. Any other advice concerning this model (and others) most welcome, but please don't flood the reply with a recommendation for every model that NIKON has ever made. We are helping a snapper up his game without confusion.

Same for me with my a6300. Initially, unfamiliar with the camera, I didn't turn my camera off after shooting, and drained the battery (only had the OEM battery at the time) pretty quickly. Quickly trained myself to turn the camera off after each shot (unless I was taking several at a time), and got a couple of spare 3rd party batteries and a charger. The other thing I did was turn off known battery drains, like airplane mode and silent shooting, and haven't had any problems since. I always carry a spare (sometimes two) if it is going to be a long shooting day. And I always leave the house with the battery in the camera at full charge.

I agree with you I have been using Win10 since day one on all my PC's (5) and my wife'e 2 PC's there hasn't been a single problem.
On the latest update which I have been using today and I have only noticed one difference, when the start icon is left clicked there are 4 buttons to click on, shutdown/restart, setting, file explorer and your MS account.
Some other function have moved to the top left corner eg, Expand, Pinned Tiles and All Apps.
I quite expect to discover changes more as I continue to play around with the latest update.