As said, you're going to have a very difficult time finding something that performs well as an all purpose lens, because they just don't make those. I mean a 12-300 f/1.8 1:1 AF-S lens. . .I can only imagine what the cost on that would be - but thats about what you are looking for.
If you were willing to spend 600 on the Tamron - split it up and get a walk around lens (18-70 - thats not the length of the lens you want, but the wide should be near 18 or so, and the long near the 70), a Telephoto lens, and if the walk around lens is limiting you in the wide landscape shots you'd like to get, then get a used dedicated wide.
There isn't a single person shooting that has one lens, that they're willing to sell every other lens they have because THAT lens does all they need it to do (well unless they have the kit lens and are cool with that).
As for what I would get:
Sigma 24-60 F/2.8 for about 200 bucks NEW.
Canon 100-300 USM for about 200-250 bucks NEW or the Canon 55-200 for less than 200.