I went back and looked at photos from the last few years and realized that on my 17-85 I took almost all of my photos at either the wide or zoom end. Very few in the middle.
That quote is perhaps your most telling of your post... so option #1, 24-70 f4 IS is not going to cut it on the tele end as the 70mm on the full frame 6D would have the FOV of "middle" focal length of what you were used to on your crop body. You will be wishing for more reach constantly when you zoom out to 70mm.
Option #2 is ok, as the 70-200L f/4 IS is one of the best IQ zooms that is light to carry on top.
But I think you should have gotten the 24-105L as it is still f/4 and will give you more reach than 24-70mm.
Just look at some of the threads here on CR where people post their pics...this so called "kit" zoom can generate some awesome pictures. And you don't have to switch lenses to gain reach or to do good quality landscapes. It is a perfect walk-around lens and a good event and portrait lens.
I am sure you will hear voices that say "oh but f4 is too slow for indoors"... Remember, 6D is very good with low light.
Importantly, all the other options you list are also f/4 so by no means would this be a step down.
If you pick 24-105L around ~$800, you can now consider other faster lenses...perhaps even the excellent 135L and still come under your budget or instead the 70-300L and get a longer tele for a few more bucks.
You can't go wrong with 70-200L f/4, but frankly you will be gaining additional 100-200 f/4 if you opt for the 24-105L zoom and I don't think this is a great "first" combo. Nothing wrong with the 70-200 f/4 IS...I am a fan...just it won't add too much in this specific combo.
Once you build up your lens collection, depending on your apetite for weight and speed, I think either the higly able, lighter 70-200 f/4 IS or the equally able, faster, heavier 2.8 IS II should be in the collection....but early in the game, not so much.