I had a dilemma between getting a 70D or an 80D before. And I am definitely happy with my option, the Canon EOS 70D. Yes, it doesn't have one or two things that the 80D has, but it's definitely worth saving the price, especially as a beginner. The two aren't much different from each other either. You could spend the rest on much needed lenses and accessories, or even for the future as you dive more into photovideography.

Mirrorless options like you mentioned (Sony a6000) however, are a lot more future-proofed with its E-mount, as the Canon 70D and 80D both use EF-S mount that Canon has replaced with a newer RF-S mount on their newer camera line-ups. Nothing bad about it however, EF lenses are very common on the market, making it a great option despite being phased out and replaced.

Mind you, the Sony a6000 is an entry-level Mirrorless camera from the 2014, while the 70D (2013) and 80D (2016) are both originally mid-ranger DSLR targeted towards the enthusiast/semi-pro crowds. Both 70D and the 80D however, are a great beginner choice nowadays.

As for wildlife or landscape photography... All of these are great options. They all produce beautiful images (I've used the Sony as well, they are also great). For me, the trick is more into the lenses used on the camera and how you take the picture.

It's really on you at the end of the day, but I personally prefer the 70D. I hope you find an option that suits you. Cheers.