You just have to find what your rifle likes. It also depends on what you are looking for. If money is no object, you could always go to a lapua testing facility and lot test ammunition. I only have ever met one person who did this. It cost him thousands of dollars in the end, because he bought many thousands of rounds from that particular lot that his rifle liked.
I’m not into paying that much per round of rimfire ammunition. I’ve always shot cci green tag in my old anschutz, and my dad’s anschutz.
I went through 37 different kinds of ammunition with my 10/22 when I put my Kidd lightweight barrel on it. I tested everything from bulk packs to around $0.18/bullet ammunition. The cci green tag was the best grouping, but cci sv was so close to it, and so much cheaper that I settled on the sv. With me shooting, it is consistently under 1/2” at 50 yards. If I shot longer range, I would probably go with the green tag. It had better sd es numbers when chronographed. The 10/22 isn’t as accurate as the anschutz 1710d hb that I used to have, but that’s to be expected. The Anschutz was right at 3/8” consistently, the 10/22 averaged .43 with sv with it ranging from about .32 to .49. Either way you’re comparing ragged holes. One federal “match” 😒 was good, the other was horrible imo at like .76”.
My only advice is to acclimate the barrel before measuring groups or velocities. It does make a slight difference, especially when going to/from waxed/plated. When you find what it likes, buy a lot of it from the same lot, or if you can’t find lot info, all that the store has at the time. Then when you find more somewhere else try it to see if it shoots the same, before buying a bunch. Don’t just shoot one group. Buy a box of 50, use like 25-30 to get your gun used to the ammunition and shoot the rest in 5 shot groups, with some time between groups, before shooting the next ammunition. If you’re testing bulk pack or cheap, you don’t need to waste your time on 50. Pop off 20 or so, and shoot the first group. If the first group is horrible, give up. If it’s good, finish out some more groups. Especially with cheap ammunition, it’s not the best group, but the worst group that you should pay attention to. The worst group generally says more about its potential than the best. Even a blind squirrel finds a nut every now and then.
It’s all what you consider acceptable. I could definitely shoot a few thousandths smaller groups with my 10/22, but it is perfectly acceptable for my uses. I mostly just shoot chipmunks inside 60 yards. Sub 1/2” at 50 yards means that if I miss, it was me, and only me. That’s what I wanted. I’m not shooting a know your limits match at 100 yards with a 1/4” spinner on the small end.
CCI green tag, Lapua, SK, would be what I would recommend for anyone to test if they want the best accuracy. If you don’t want to spend $$$, cci sv, federal automatch, were my two best shooting cheap ammunition. Federal gold medal match was like a mid grade one was good, my gun didn’t like the other.