Lee FK filter holder vs. Cokin Z-Pro holder

So my Christmas gift this year to myself is filter set. I've been using Cokin P filter ever since. When moved to full frame, it became a little harder as I had to hand held filters bc the P-series holder will get in the frame when I do landscape at 16mm.

I ordered:
- Cokin U960 kit: filter bag, holder, Z121L, Z121M, Z121S
- Lee ND 0.9 proglass
Then I experienced problem with Cokin holder being in the frame at 16mm. The only way to remove the vignetting and holder getting into the frame. So I ordered Lee FK holder with wide angle ring adapter WAR077.

Below is the Cokin holder and Lee holder with different configurations form worst case scenario to setting that is close to the lens' vignetting itself.

First off, the base line with no filter. Then UV screw on filter on (or polarize to some people), combination with Cokin rear and front first slot, Lee with 2 and 3 slots.

No Filter

B+W UV screw on Filter

B+W UV screw on Filter and Lee adapter ring WAR077

B+W UV screw on Filter and Lee adapter ring WAR077 and Lee FK holder with 2 slot

B+W Filter and Cokin Z-Pro adapter ring

B+W screw on Filter and Cokin Z-Pro adapter ring and holder loaded in rear slot with 3 slots in front

No Filter. Cokin Z-Pro adapter ring and holder loaded in rear slot with 3 slots in front

No Filter. Cokin Z-Pro adapter ring and holder loaded in rear slot with 3 slots in front, rotate so that holder in portrait mode

No Filter. Cokin Z-Pro adapter ring and holder loaded using first front slot. Holder only has 2 available slots for filters. Rear slot leave empty

No Filter and Lee adapter ring WAR077 and Lee FK holder with 3 slots

B+W UV Filter and Lee adapter ring WAR077 and Lee FK holder with 3 slots

Bottom line:
They are both worth every penny ... depend on what you shoot.

For Cokin:
If your lens from 20mm and up, you should be ok with Cokin filter 3 slots. If you shoot at 16mm, the best way is to use first front slot which then only leave you with 2 available slots for filter. But then the first front slot is not usable anyway to my opinion. This first front slot has bigger gap (for polarize?) and the 3 pins in the way so if you load a 4"x4" filter in this slot, it will most likely be scratched and doesn't hold in place well. So Cokin holder is great if you use 20mm and up or with polarize filter with 2 slots setup, so basically you only left with 1 slot open after polarize is in place. I've read online that Cokin works better holding the polarize filter. 
COKIN PIC SLOT FRONT REAR

Cokin 77mm adapter ring in original rear slot as it suppose to

Cokin 77mm adapter ring in first front slot and leave only 2 available slots for filters

Cokin first front slot seem to have bigger gap than the other 2. Not recommend to use with slide in filter

For Lee:
It's clear from frame with 3 slots and all 3 slots are usable. The only time you'd have problem is if you use screw on filter and 3 slots. and Lee, to some people doesn't work well with polarize filter.

Design:

I have both filter holders on Nikon 16-35mm. Standing ruler starting from plastic ring next to front element.
Lee holder is about 13/16 in high while Cokin is about 1 and 1/16 inch thus it does get in the frame a little. With certain setting the screw of Cokin does get in frame as well. So the convenient of thumb screw has its price. While the less convenient screw from Lee is completely flush.

Lee holder hight

Cokin holder height

Cokin (Left) compare to Lee (right). This is one single slot taken out.

 Material wise, Cokin did a great job with their molding process, Lee holder slots has some over molding debris left over

Lee's slot edge

Cokin's slot edge

Lee's slot edge front view

Cokin's slot edge front view

For me, I don't use polarize, and I use ND 0.9 with GND 0.9 most of the time with sometime another GND0.6. So Lee holder works best.

Other review:

http://www.2filter.com/Leefilters/CokinZvsLeeFilters.html
http://darwinwiggett.wordpress.com/2011/06/28/lee-holder-vs-cokin-z-pro-holder/

Where to buy:
I was lucky enough to be able to order what I needed when I needed them without on waiting list. These suppliers are fast and reasonable on shipping charge and timing.
http://www.bhphotovideo.com/
and
http://www.2filter.com/