If you are wanting a 'super zoom' for Canon full frame, under $1000, you are out of luck, and likely always will be. Canon will never offer a lens like that in the $1000 or under price range. Nikon's 28-300 looks like a superb lens (at least from the test at thedigitalpicture), but I despise the Nikon system.
I bought the Sigma 120-400 for around $900, and use it on my 6D. I prefer to use it on a monopod, because it is about 4 pounds. I feel it is as good as the Canon 100-400, but costs half the price. Also costs 1/3 the price of the upcoming new Canon 100-400, which will be forced to sell around $2500, because Nikon's new 80-400 costs $2700. Tit for tat. "L" lenses are never going to be as affordable as they are now, but then neither are third party lenses such as Sigma or Tamron.
I'm not sure if you are wanting a "walk around" lens or not. The lens that will give the best image quality, reach, and combined with light weight, is the 300 f/4 L IS. The best "walk around" zoom lens is probably the 70-300 f/4-5.6L IS. But both of these cost higher than your budget, about $1300 to $1450, depending on if there is a "sale". You could always buy a used lens, but that's not the best way to spend your money...unless it is very mint condition, and no accumulated dust inside.
The 70-200 f/4L without IS, at around $600 and only 1.5 pounds, is by far the best value in the entire Canon lens lineup, in my opinion. However, 200mm may not be enough "reach" on the 6D, for what you are wanting.
There are many users on here and elsewhere, who are happy to spout that the 70-200 f/4 (non-IS) is a "soft" lens or otherwise not worth owning. But I say they either got a bad copy, or else want to justify spending more than twice the price on the IS version, which is as heavy as the 70-300L, but only goes to 200mm, and is a waste of money in my opinion (at least since the 70-300L came out). At the full frame corners wide open, my 70-200 f/4 can get a tad soft, but I close it down a bit if I need sharpness there (usually at infinity focus).
I have rented the less costly 70-300 Canon, but only used it on a crop body. I liked it ok. For $600 or less, it's kind of a halfway decent value. Autofocus was fairly slow. I'm not sure how good/bad its image is outside the crop area, either. I had considered renting the much touted Tamron 70-300, but apparently I read something that made me think the Canon was sharper, so I rented it instead. It was certainly more than sharp enough on the crop body, but the color palette and the contrast definitely were not as good as my 70-200 f/4L, and the sharpness was a tad behind also.
If you are wanting to do macro shots, I would say try the new Tamron 90mm f/2.8. Read some of the user reviews on amazon, or elsewhere. The longer macro lenses cost considerably more than $1000. Not sure if macro is necessarily what you are wanting, though. Certainly you can buy extension tubes and do macro photography with any lens. The Canon 100L is a very popular macro lens, but it's never gotten me excited.
I have rented the Canon 24-105L, and despite some chromatic aberration, I loved the color and contrast of that lens. I decided ultimately to not buy it when I bought the 6D, because I feel they will never sell it in the "kit" at as low a price as I would pay...around $580 plus the body.
The 24-70 f/2.8 lens I crave is the Tamron, but I actually need something wider to use first. I suspect you are probably not really looking for a 24-70 at this time.
My favorite lens is the 135 f/2L. It costs just under $1000. It has the best bokeh of any lens I have ever used, rivaling that of the 85 f/1.2L...and had no "bokeh fringing" to boot (the 85L has a hefty amount at the wider apertures). Its sharpness might vary from one copy to the next, but mine is very sharp.
The 135L may or may not be the best lens for you, though. I suspect the 70-300L might be. You would need to go a bit above your budget.