or I should ask which do you prefer or use and why? I read there isnt much difference, but would like others opinions on the 2.

 

What are you wanting to put these oils in? I quit using synthetic oils in all my vehicles. One they are too expensive, two I can't see where they are any better. For 45 years I have run Dino oils with no problems caused by oils. I have lived & driven in temps from -25 degrees below zero to +120 degrees. From sea level to 8000 ft in elevation.
If you are going to put it in a NEW Vehicle then personally if I was given the choice of the two I would use Mobil One. WHY, because I can buy it almost any place @ anytime.
I have used both. In my days. Just my two cents.

 

I'm going to put it in my new 2012. From my past experience with Mobil 1 on my last car it did save gas. Not a whole lot, but enough for me to want to spend extra on it and not have to change the oil as often.
I've always used Mobil 1 because of the fact and what you said that you can buy it almost anywhere although now with my car needing 0w-20 only Advanced Auto has it. Surprisingly walmart does not carry it here. Some people swear by Amsoil and say it's better, but I personally dont know anyone myself who uses it.

 

amsoil is better use it in all my cars. better TBN and viscosity and better lubrication in cold temperatures. mobil one is good too though so you would be safe using either one.
one reason I use synthetics and one that does tend to get overlooked is it is better on gaskets.
I have had to replace numerous oil gaskets using dino oils but never had to using synthetic oil.
just my two cents worth.

 

dont know if its better but i use mobil 1