135mm or 200mm?

I don't see how anyone could tell you which focal length you would use more. This sort of thing varies a great deal from one person to another, and you ought to know your habits better than anyone else could.

A 200mm lens covers about 2/3 of the width of a 135mm lens's view. The difference is pretty significant.

Since you have zoom lenses covering 24-300mm, what is your goal in buying more primes? Are the zooms inadequate? Do you need faster apertures, or sharper images? I would think that if you look at how you use the lenses you have, and how (if at all) they fail to satisfy you, that should tell you what additional lenses you should buy.

I can say that the FD 200mm f/2.8 SSC is a very nice lens, though fairly large.

I am going to buy another prime and can't decide between the FD 135mm and a FD 200mm.

I went through a similar 'think-time' deciding between those two focal-lengths. I opted for a compromise by getting myself a 135mm along with a x1.4 converter. I am a Canon person (is why I said mentioned the x1.4). I do believe the Nikon conversion adapter would almost give you the capabilities of both the focal lengths you are pondering about. Good Luck!

Craig, I was merely asking for personal preferrences from landscape photographers.
Incidently, I have a Canon FD 2X converter, bought it 4 years ago and never used it.

The FDn 135/2 is a favourite prime of FD users, and is surely sharper than the 200/2.8.

I would suggest, however, that you consider acquring an FDn 80-200/4 L. Most agree that it is the best FD zoom ever made and, furthermore, that at 200mm it is optically superior to the 200/2.8. And it sells for surprisingly little these days. You'll likely will be able to find one for the same price as either of the aforementioned primes.

Ditto on what Mark said. I never had the 135/2 but I had two versions of the 200/2.8 and the 80-200/4 L. The L zoom is superb!

Good advice, because I already have the 80-200 (non-"L") I never gave it a thought. Having used Nikon Digital (D2x) for several years I had become partial to Nikon primes....they truly are better than even the 24-70 I have. Also my FD 50mm F/1.4 is a vey good lens.

The 80-200 is great as everyone says, although you have to like push-pull (they disappeared for a reason), and it does have some distortion.
Don't rule out the very sharp, light, and cheap 200 f4.

(i) I agree with all the comments so far.

(ii) You're a landscaper, so let me offer a contrarian view. For landscapes, you'll probably use the tele at a small aperture, like f/8, give or take a stop. At that kind of aperture, all FD lenses perform very, very well. You might consider a simple 135/2.8, which is small, light, and can be found for next to nothing. (That's much the same advice as Scott's, to check out the 200/4.)

(iii) If you took portraits at wide-ish apertures, the best bang for the buck is arguably the 135/2.5, which is a breechlock lens from the 70s. It has really nice out-of-focus rendition, and you can find one for less than a hundred bucks. Downside is it's heavy-- has a big thick element near the front.

Yes, the 135/2.5 is a treat. Another very fine FD lens for portraiture is the oft-overlooked 100/2.