Which is the easiest to install s1156 cooler?

I have the same problem on a 1366 . I hate the push pins . I tried a Zalman and it was so big I had to remove the fan to get to the screws and then could not get the fan back on. Who knows of a simple yet reasonable size cooler??

The CM Hyper 212+ is not too difficult to install.
The Thermalright MUX-120 is even easier and comes with a silent fan and very good paste.
The Thermalright also has minimal dimm intrusion which means it can be mounted on a board with tall ram.
I have both coolers on 1156's.

Would the corsair h50 be an easy to install and a good performer for an i5 750?Or would megahalems be a better choice?

The H50 is easy to install but requires a good mid-size case that can accomodate it.
The Megahalems is generally considered the best performing air-cooler.
It sounds to me like you want to oc your cpu to 3.8-4.0 MHz.
Something you should have included in your thread.

I don't want to oc my cpu to 4ghz,but I live in a very hot country so my temps are pretty high.Every attempt to reseat the old cooler has done very little.But I would like to oc my cpu considerably high (3.6-3.8) as you said,but my main concern is to have a good performing hsf to keep the sound levels of it's fan as low as possible.My pc is described in my profile and my case is cm 690 which should fit the corsair h50 and the megahalems.

Yep! you have very nice gear that can support either one of those cooling options.
H50 or CoolIt are good liquid cooling options.
For air-cooling a Megahalems,Thermalright Venomous X would work fine.
Add two Scythe fans S-Flex or Slipstreams and you'll be fine.

I bought the CM hyper N250 and it was very difficult to install!!!! First you put little brackets on the heat sink with threaded posts on them ( easy ). However there are three little cutouts on the brackets for each proccessor . Not so easy to keep the 4 posts in the right positions. Now you slide the heat sink with attached brackets thru the mother board and hold another bracket from the backside in position while you put the nuts on the post with your 3rd hand !!! I had a motherboard I could remove and it was still a son of a #$#@. If the H50 212 is like this it is not easy.

That's one out then.Thank you for the info.

CM TX-3. It uses pushpins but they are really easy to install. And if your like me (experienced with all sorts of Heat Sinks) this one actually feels firmer when installed than say a Coolermaster 212 which requires a back plate. And when you install the push pins, use a flat head screwdriver to press them in, not your thumb. If it takes more than a little pressure, rotate the plastic heads 90 degrees. It's hard to mess it up.