Just wanted to share this terrific review of many ammo varieties. They shot 5*5 groups of each ammo at 50,75 and 100 yards using a "highly-accurate Swiss-made Bleiker rifle, with a 2-stage trigger". Looks cool and expensive...
According to this, the Eley Match ammo is the best, and pretty good value. It's interesting how some more expensive ammo of teh same type like the Eley tenex is actually not as good as 2nd tier varieties.
http://www.accurateshooter.com/guns-of-week/22lr-rimfire-ammo-comparison-test/
You can click though to the actual results to see the shot groupings themselves!
http://forums.accuratereloading.com/eve/forums/a/tpc/f/8711043/m/9871088921
I added up the groupings for each ammo and ranked the top 15 here for you. The lower the better.
Eley Match 0.994
Lapua Midas M 1.059
Eley Tenex Ultimate EPS 1.068
Lapua Center X 1.119
Lapua Polar Biathlon 1.161
Lapua Midas Plus 1.209
Eley Match EPS 1.273
Lapua Master M 1.375
Lapua Midas L 1.387
Eley Tenex Semi Auto 1.39
Lapua Standard Plus 1.445
Lapua Master L 1.454
Eley Tenex 1.517
Eley Club 1.647
Eley Sport 1.725