David Clarke H10-13.4 as stated above.
You only need to buy noise cancelling if you fly several times a week. But if you did you wouldn't be asking.

Buy new - on special offer at various places from time to time.
Buy second hand on ebay - but only the newest model (do your own homework here) - and expect to have to have it serviced, thereby bringing the cost up to the same as new......

You can get some folks to convert the trusty H10-13.4 into ANR capability. If you want to.

Except if it doesn't fit your head!

I have a Lightspeed Zulu 2 and really like it. I've just had to buy a new one, because my original one was stolen. I looked briefly at the PFX, but declined. It is more expensive, takes four batteries and the dealer told me the battery life was shorter. However, the main reason I decided to stick with the Zulu 2 was that the battery/control box on the PFX is about twice the size of the one on the Zulu 2 - it's like a brick.

I would recommend David Clarkes. They're robust and reliable. Mine have about 7000 hours on them, much of that instructing. Like the Eveready Bunny they just keep going and going and going.......

What ever you do, DON"T even think about the many DC look a likes. Nearly everyone I've seen is crap.

No contest, Bose every time for noisy GA aircraft. Expensive but worth it for the reduction in noise fatigue. Need a bit more TLC than a pair of clunky heavy old DCs, but very reliable.

bose a20
 

I want to buy these headsets...
Where can I find them in Dubai?

The best thing you can do is actually GO somewhere and try them out. My local dealer had a sound cabinet to simulate different environments (GA open cabin, 1 Mot, 2 Mot, turbine, Heli etc) and you could then judge the individual sets.

I went there thinking to buy a Sennheiser or perhaps Bose but the Lightspeed Zulu fitted best to my head, the Sennheiser sort of "perched" on it, DCs clamped my head tight and Bose seemed to crush my ears. I ended up buying the Lightspeed Zulu, have since upgraded to Zulu.2 but didn't see much difference to the Bose - except when viewing cost and Bluetooth capabilities.....

While I was being trained to fly I used the rental David Clark H10-13.4 and the ASA AirClassics HS-1A headset, and between the two, the David Clark is just a lot more comfortable when I was on navigation training.

After I earned my license though, I bought the Sennheiser S1 Passive headset while Sennheiser had a discount on the headset. The Sennheiser was a bit more comfortable then the David Clark H10-13.4, but then I'm paying a good $30 more then the David Clark.

It's all really your choice. You just have to pop in to your aviation club and try the headsets out (if they sell them), or just find a nearby aviation store. I got lucky with the Sennheiser because I didn't try it before and there's a decent chance it doesn't fit well to my head.