Canon, Nikon, Tamron, etc, all seem to have a decent low cost 70 to 300mm zooms. I bought the Nikon one, and wasn't all that happy with it. It's not a bad lens by any means, it's not bad at all, but at the full 300mm extention I found it a bit soft. Mileage for others might vary. I ended up trading it back in, and went back to some of my old Nikkor glass. I found my old 300mm F4 manual focus Nikkor was sharper, and true no VR, no AF, but I often use a monopod to begin with and it's not all that hard to focus at infinity.
Also I have one of those old 70-210 constant F4 Nikkor zooms that Nikon only made for a couple of years, I think that was back a good 20 yers now. Anyhow, I find it an extremely sharp lens. No VR, and some people complained the AF on it was too slow compared to other lenses, but when I compared side by side shots - say that lens and my 70-300, both set at 100mm or 200mm for example, the older Nikkor was always seemed to have that better edge, clarity, sharpness, etc. Again, for others, your mileage may and will vary. Sometimes arguing over which brand of lens is the "sharpest" is like arguing which brand of ice cream tastes best.
So for me, at the lower level, some of the work I have seen done first hand with Tamron and Sigma lenses, I think they have come a long, long way from years ago. At the pro level I find the Canon and Nikon lenses still the best overall, especially with zooms.