the longer the zoom range, the crappier the lens, with few exceptions.
It is pretty much impossible to make a lens that goes from wide angle (28mm) to telephoto and have it be sharp throughout.
To make a lens like that light, it would have to be very slow (doesn't let much light in.) Most are poor quality, focus slowly, have small apertures and not at all sharp.
I prefer all my lenses to be 2.8 or faster.
I'd rather have less zoom range in a higher quality lens than more zoom range in a craptastic lens like the Tamron 28-300.
A lot of people like the Nikon 18-200mm lens, but it isn't really sharp throughout and gets mixed reviews. Some love it, some don't. I'd rather carry a 28-75 2.8 and a 70-200 2.8.
The only long zoom ones I could really recommend are the:
Sigma 50-500 Bigma
Canon 100-400 4.5-5.6L (still slow)
Canon 24-105 4L IS
Nikon 200-400