Green Tag is great ammo but unless you are a damned great shot (Olympic team or similar) I doubt you could really discern the difference between CCI standard velocity and it. For 99% of us probably not worth the double cost, but shooting is a mental game also, so if you feel it helps you and you compete, use it. Otherwise CCI SV, Mini Mags (hi-vel.) or Federal or American Eagle (hi-vel) works pretty well for me.
One other thing I'd like to mention while we're at it............
I have a CZ 453 American .22 with a single set trigger and a 3-9 Leopold Scope which I consider to be competition grade rifle - even though it's not set up to look like one. It will consistently shoot one hole groups at 100 feet all day long when bench resting it on sand bags. Will do that with just about any ammo including Winchester Wildcats, Federal, American Eagle, etc (all high velocity ammo). I was curious what it would do with real target competition ammo so I bought the two top of the line Eley offerings which are standard velocity and world renown for accuracy. The CZ HATES the Eley! I could not group better than 1/2" groups with it. I called CZ and they confirmed that their barrels are slightly tighter and won't shoot true target grade ammo as well as the run of the mill hi-vel stuff. Since the Eley is so expensive and the CZ handles all other promo ammo so well, I could not be happier.........
My model 41 also shoots about anything fairly accurately, but it really likes the CCI SV 40 grain or the Remington Target SV. When I used to run .22 matches at our Club most shooters used the CCI or Remington SV 40 grain ammo, not Green Tag or Eley.
My M18, M63, Colts, Marlins, Winchesters, don't get too fussy and I usually use what ever Hi-Vel 40 grain stuff I have.