What would your suggestion be

So, I have a Canon 6D, Canon 24-105L, Canon 100mm L.


I was thinking about another lens soon to add to my collection.

Things I shoot:

Portraits - Normally shot with my macro since I love the quality and being that close up with very fine detail but it IS a pain in the rear to use. Although up until this point I did not have studio lighting.
Skateboarding
Long exposure/ HDR landscape
Concerts (But a lot of the time I can be on stage or right in front)

I may end up getting into weddings soon but my plate is full with working full time in the Navy and trying to do photography + school on the side.

I honestly want something like the 15mm fisheye but I'm not sure. Since it would mainly be skateboarding/landscap​e/long exposure I feel like I could get a cheaper non canon brand.

What seems lacking or what is your most versatile lens.

Oh, lenses I've owned and got rid of for one reason or another. Normally because I wanted a multipurpose in its place. the 70-200mm I sold but I feel like I may honestly need one back, just maybe a cheaper option. Also loved my 17-40 as well
I really LOVE the L series lenses I have. Amazing quality etc.

70-200 F4 IS USM
50mm 1.4 canon
85mm 1.8 canon
17-40mm F4 Canon

It all depends on what you want to shoot. I have the 85 1.8 and it is a stellar lens for Portrait, sports and concerts. The 4th area of long landscapes it could do, but not really where this lens will show what it can do. I do low light action sports and being able to dial it down to 1.8 really makes a difference.
As for the landscape, I also happen to have the 17-40 and it is a great lens. One of the better ones for the price. I would look at the Canon Refurb site for both if you don't have a time frame. I got my 17-40 for $571 on sale. And the 85 1.8 is cheap, but refurb saves you a few bucks and I have had nothing but good gear coming from refurb at Canon. Good luck with whatever you end up with.