I like the 28-135 lens but am interested in using the Rokinon 24-85 T1.5 lens kit instead.
I can add the 135 + 95mm variable filter for the same price.
How do they compare in Video image quality?
Is the Sony E lens worth more than 5 of these because it can AutoFocus with PowerZoom?
Should I avoid lens changes and save up for the Sony 28-135 f/4 cine lens instead?

My dilemma is which mount to choose if I go with the Rokinons?

I still have a collection of Pro Nikkors and do not want to give up on a future Nikon FullFrame MirrorLess camera. These lens work really well with an adapter on my A7s. So I assume, I could use the same adapter with these Rokinon lens and later on use them native to a Nikon Camera body.

Nikon mounts are more adaptable to other cameras if that is something of value to you.

The times I've used the Rokinon's I've found them pretty decent - though I actually like the look of some of my older Nikon lenses better...

However, you're talking about a whole different style of working when you use primes. It all depends on your needs and what you're shooting, because the question is whether you need a zoom with a 5:1 range - that also will hold focus. I personally find myself using zooms a lot - but this is because I shoot a lot of documentary interviews and my clients tend to want a variety of framings - and there is no time allowed to change lenses during an interview. The 28-135 may not be as fast or sharp as some of the larger cine zooms, but it makes a pretty decent image for a lens that's less than 1/10th the cost of most cine zooms. And of course if you have a shoot with an FS7 you're already set with a lens...

I got the Sony AF 28-135 f/4 Cine lens instead and could not be happier.
It covers the entire range I need and is now dedicated to the A7s.
The only time I've had trouble with AutoFocus, I merely pulled the ring toward me and moved it less than 1/8 inch for perfect focus as witnessed in 2X in my 7" HD Monitor.