I usually steer people toward last-generation (or more) models for the best value on a budget, and that's especially true with Canon's entry-level dSLRs, the Rebel series in the US. Canon tends to trickle down technology from older, higher-end models whose prices have dropped, and it just makes sense to buy those better models instead of the new one with the ancient insides.
But the Rebel T7i (called the 800D in the UK and Australia) represents Canon's first truly significant update to the series, really since thein 2010. The got a new-to-it sensor and autofocus system in 2015, but that was a transitional change. But somehow, Canon manages to make this big change feel incremental: It delivers roughly the same photo quality as before and shoots a little bit faster once you discount how fast the lens drives. It still doesn't really match the Nikon D5600 for photo quality or continuous-shooting speed, though it still has the lead for video autofocus.
The camera costs $850 with the 18-55mm f4-5.6 STM lens (£895, AU$1,400) though regionally other kits are available.
The T7i's body remains the same as its predecessor's, but it finally incorporates Canon's Dual Pixel CMOS sensor, a 3-year-old technology with on-chip phase-detection autofocus that's in almost all Canon's other interchangeable-lens camera lines. But it's a current sensor and metering system, the same ones that are in the, but with an even newer image-processing engine (Digic 7).
Canon still uses an antialiasing filter, which blurs edges slightly, on its sensors; Nikon does not. So Nikon's shots look tons sharper than Canon's. And Canon's automatic white balance isn't as smart in cloudy conditions (or situations where the light color is similar).
While the T7i doesn't look as good when you do side-by-side comparisons, judged on its own most people will be quite happy with the results they get, especially if you'll just be viewing the photos on a mobile device. The colors pop nicely, skin tones look correct and it has a dynamic range that meets the expectations for its class -- like most low-to-midrange cameras the default settings increase contrast, which means you lose some detail in the brightest and darkest areas.
If you shoot raw, you can pull out a lot of detail from underexposed areas, though not in overexposed areas. Once again, that's pretty typical for this class of camera. In practice, you can shoot as high as ISO 3200 -- that allows for relatively low light, like the level in a bar -- without worrying about noise or other artifacts.
The camera's adequately fast for typical kids-and-vacation photography, but it doesn't support continuous autofocus and autoexposure on its High setting. The camera doesn't automatically drop back to low or simply deliver a slower burst like it did with the T6i, so if you have it set to continuous AF and High-speed continuous shooting, don't be surprised when the shots come out inconsistently exposed with only the first few in focus. The safest thing to do is keep it on the slower setting (4.5 frames per second).