When you say all types of Nikon equipment you seem to be referring to entry level / amateur gear (judging by your list).
I think you will find that there is much more difference between Nikon and Canon entry level and Nikon and Canon at more advanced levels than there is between the brands. I would be very surprised if a similar level of canon camera and lenses would give you notably better (or worse) results
If something is approaching you at 300 mph it is unlikely that a shutter speed of 1/25th will be suitable.
Having said that, I would expect to be able to get decent results with a D90 (which is similar to a D300) or a D3200. If I was looking to get better results with your kit I would start by getting better quality lenses.
If you want specific advice on how to get better results with your existing equipment try posting a photo you are unhappy with, for people to offer advice (I'm sure there are a number of airshow enthusiasts on here)
I have tried all sorts of Nikon digital equipment and can't get crisp magazine type shots of propeller type aircraft comming at me at 300 miles an hour! I try to get the shutter speed between 1/25 to 1/500. F 11 usin D3200. D90, D100 Bodies and 70 to 300 to 18 to 55 Nikon D Lenses.( PROG.A.M. modes etc.)
Getting blue blur vignetting on edges of image and metering struggles in variable lighting, ie clouds sunshine etc?
Shall I dump the Nikons and start again witn Cannon Stuff?....or is it me?
I don't use less than 1/500th shutter speed for horses never mind planes.
Besides that with the 300mm @ 300 on a crop sensor, nikon i believe being 1.5x would indicate a hand hold shutter speed of at least 1/450th to cut motion blur, then a slower shutter to get prop motion or a good panning technique to get background motion.
I don't shoot aircraft, so wouldn't normally comment; but having seen the stupid pie chart above, feel compelled at least to try and be helpful.
You'll probably want to use whatever the continual tracking focus mode is for your camera, on canon it's called A1servo, Nikon will have an equivalent. Also your shutter speed ought to be at least a match to your focal length ( plus crop factor) so if you've a 300mm lens and a crop factor of x1.5, that'd mean a minimum of 1/450th shutter speed to avoid shake. I'd guess at range, an aperture of f8 would be all enough, some lens get noticeably less sharp by f11. Might be worth thinking about spot exposure too, so the item you focus on is well exposed, the sky probably less so. Practice panning smoothly to give the camera a chance to autofocus and have the drive in multiple exposure mode to catch a series of pictures as the plane zips by.
You might have to bite the bullet and get a quality zoom lens to stand much chance with this style of shooting, I'm guessing a 300mm is a useful length though.
Hopefully, someone who does this a lot and isn't intent on acting the donkey, will come along and develop further.
Whatever comes to hand. It's not the make of equipment that matters but how you use it.
As for settings, I have shot a fair bit of aviation stuff over the last quarter century or more, mostly military helicopters and low-flying transport aircraft, and soon found out that as a rule of thumb most side shots work best at 1/160th and most head-on shots need much faster. This one was shot at 1/640th at ISO160 as a compromise because I didn't want it to look like the Merlins were unsupported by their rotors but I also didn't want the airframes to be too blurry yet needed a bit of depth of field and didn't want to silhouette. If I had been able to set the shot up rather than having to take this 'on the hoof' (I didn't know the formation lead pilot was going to set down pretty much right in front of me) I would have shot it differently, but out in the real world you usually have to make instinctive decisions and hope for the best.
For the one below I had much more time to set up the shot, I had better light and I was also able to position myself to the side so I was able to shoot at 1/160th and F11 to get both main and tail rotors slightly blurred as well as having the scene-setting Chinese MiG variants in the background still reasonably sharp.
Personal experience, built up over time, and gut reaction are often the only things to go by.
OK will pop in a tip for you. Good panning technique is needed, especially for propeller aircraft (or if you want to give an impression of speed). You can practice this almost anywhere there is moving objects (cars, birds etc). Stand with your shoulders square to where you want to take the shot, then turn your body 45 deg left, keeping your feet still. Focus on your subject and follow it through 90 deg, finishing 45 deg to your right (or from right to left if needed). I take the image when I'm square-on, or sometimes a little earlier if I take a sequence of shots. For propeller Aircraft, a shutter speed from 1/80 up to about 1/320 will give some prop movement, for fast jets, use a shutter speed of at least 1/500 - I usually switch off IS too.
Below is one taken at 1/80 on a 300f4, not flying, but still gives an idea