Is the  majority of scope makers doing 30mm or 1 inch tubes? what is the average, I wanted to get the scope mount from armalite and was'nt sure which one to get, considering i might be upgrading scopes in future, i wanted it to fit the majority.

Scope tube diameters.  

The 1" tube is the standard for most American made scopes used for hunting and general application.   Scopes with 1" tubes start at under $100, but better optics will cost say $200 to $600.   It all depends on what you needs are.

30mm Tubes are common on European scopes for all applications and also on Americal built scopes that are intended for long range shooting.  The larger diameter tube allows more movement of the internal lenses thus more elevation adjustment for shooting long range.  Most 30mm tube  scopes are very good and prices start at around $500 and go up to $1,500 or so.

This is not to say that you cannot shoot long range (beyond 600 yards or so) with a 1" tube scope, but the best scopes made for long range work will have 30mm tubes.

Let us know what type shooting, distance you plan to shoot, what rifle you plan to put it on, and your budget, and we can give you a suggestion or two on scopes.   Some of us have been looking/researching this stuff for a long time!

Assuming you are putting the scope on a 50BMG, then I would suggest you get a 30mm tube scope because as you know 50BMG has a lot of long range potential and thus you will likely need all the elevation travel you can get.

If your budget allows the Nightforce NXS is one of the best scopes available for 50BMG rifle, great optical quality and super strong.  The 5.5-22x56 would be my top pick for most any long range 50.  It is in the $1400 price range.

At the other end of the spectrum is the Busnell Elite 3200 10x40.  Priced at $180 it has target turrets and a 1" tube, but will certainlty get one started.