Both!

In fact, I have:

70-200/2.8 IS (first version)
70-200/4 IS
85/1.8
100/2.8 Macro
135/2

I don't have the 200/2.8 both because I have the 70-200/2.8 and because the 135/2 works very well with a 1.4X teleconverter to act as an effective 189/2.8.

If I ever have a large enough studio to justify it, I might get 200/2, though.

I use the zooms for sports/action, kids and pets.

But, at the most the zooms are f2.8. Sometimes larger apertures are needed. And I prefer shooting with primes, whenever the subject allows, and the 85/1.8 and 135/2 are both a lot more compact and black, so are less "in your face" than the large, white 70-200/2.8.

The 100/2.8 macro is a different beast. It's not fast enough focusing for many types of action, and not really my favorite lens for portraiture, either. It's too sharp for portraiture.

The 85/1.8 is a very nice, fast focusing lens. The only thing I don't like about it is the clip-on hood (as opposed to bayonet mount that most Canon lenses use)... I thought it would be easily broken, but it's held up well and I've been using the lens for about ten years. It does come off easily, if bumped.

The 135/2 is a spectacular lens, especially for portraiture. Use it wide open for a sort of lyrical and dreamy look... Or stop it down for very sharp shots. For portraits, it just has more "magic" than the 100mm macro lens, IMO. These were shot with 135/2, the first two on a 7D, tho I actually prefer it on full frame such as 5DII used for the third and fourth image...
https://farm9.staticflickr.com/8364/8346991484_597904a0ec.jpg https://farm6.staticflickr.com/5064/5621528555_a87f15f38a.jpg
https://farm9.staticflickr.com/8483/8265507890_56bd33c2d8.jpg https://farm9.staticflickr.com/8051/8112941582_436a1bfe8d.jpg
The last shot (of my old cat) is wide open f2.0 and near the 135's minimum focus distance, giving you some idea it's potential for background blur (very muchg limited by Internet resolutions and image sizes!)

The 85/1.8 may not be quite as special as the 135, but is certainly very capable too...
https://farm4.staticflickr.com/3456/5805118576_8f2c0ca5c0.jpg

Both the 85/1.8 and the 135's AF are very fast and fully capable of any sort of sports/action shooting.

Note: the 85/1.2L is a fantastic portrait lens, too. It produces image qualities similar to the 135/2, maybe even more-so. However it's noticeably slower focusing (by design... due to very shallow DOF potential, it needs to emphasize precision over speed). So it certainly wouldn't be my choice for sports and probably is not as versatile as the 85/1.8. On the other hand, if I were a wedding photographer I'd definitely want the 85/1.2L, too.

For versatility, I'd recommend the zoom first. It's AF certainly is no slouch, either. With max of f2.8, it's not quite as capable of strong background blurs, but uses 8 or 9 curved aperture blades to render very nice bokeh. The new Mark II is very sharp and high performance. It adds fluorite to the optical formula (which only the 70-200/4 IS also uses, among the five versions of EF 70-200 Canon has offered). It also has 3 to 4 stop stabilization (same as the f4 and up from 2 to 3 stop on the earlier f2.8 IS). Later you may want to add faster primes. But that often comes down to personal preferences. If the 70-200/2.8 IS Mark II is too pricey, if you can find a used one, the original version of the lens was now slouch, either...
https://farm9.staticflickr.com/8350/8228353946_923d2ab512.jpg

Wolf, as Magic has asked, what are your uses? If I had to guess I'd say you are landscaping as you shoot with the 6d. NOT an action camera.
Do you need the speed of the zoom?
Personally I shoot a lot of sports and don't have the 2.8. I have the cheap little $600 f4. It's super light and small and negligible sharpness-wise. For outdoors you don't need ANY speed.
Someday I will have to break down and get the 2.8, but NOT because I need the speed as I have fast primes for those duties. I will need it just so I can take advantage of the extra sensitive focus points that are activated by lenses f2.8 and faster. It's the reason pro sports shooters use them outdoors, along with the 400 f2.8. Not for the speed but for the extra hit rate while focusing.
It's a great lens if you have a use for it, but there are a lot of special lenses that may do a better job, like the 135 f2.
Give us a lot more info and we can be more specific. ;-)
If money is no issue, by all mean, get them all! :lol:
SS