Cem
I choose Nexus housing because of the compactness and small form factor (compared to other housing brands). It also weigh less than most housings if not all. Packing for travel is easier.
I also like the small diameter of the 10-17mm port. I do some wreck dives and do some light penetrations into wrecks if permits. The small port allows be to maneuvoure in tight spaces without worrying too much of scratching the port surface. The 8" dome ports may not be so lucky.
Another reason is that I can quickly move my housing to follow sharks motion with the smaller Nexus 10-17mm port. A 8" dome is slightly unwieldy. The 8" port also traps air and due to buoyancy, the camera housing tilts upwards.
Last reason is because I like to fire my strobes optically. Nexus housings has optically fiber connectors. The optical fiber cable is easier to maintain and light and cheap. Can even DIY. Also we can use S-TTL with the Inon strobes, thus eliminating the need for TTL converter. Electrical sync cords are bulky and costs many times more than optical fibre. Nexus housings, though, has an option to have 5 pin Nikonos bulkhead install.
All in all I got the Nexus at a good price from overseas and it represents good value for money in many sense.
Strobes wise, I have used Inon for past 5 years since D180 days. S&S strobes are decent too, eg YS 110Alpha. I shun Ikelite cos of it's non AA batteries compliant! 
I got Inon strobes of its compactness and price too. Sea&Sea strobes are around the same category. Ikelite strobes are big and more expensive. PM me for prices and where to get. Warrantied products
PM me if u have questions. I would love to explain to u more
Thank you for all your help.
Now i am sure that i will buy two different ports for macro and wideangle lenses..
Does anyone suggest any other lenses or can anyone say that buy this lens , this one is better?
Kirk and wideanglelens:
Why your first pick is Nexus? I was thinking on Aquatica or İkelite.
And for the strobes Inon's S&S's or İke's? which ones as we compare money/performance??
Thanks alot
Cheers
Cem