My suggestion is a little different. Pick something cheap and readily available, and run about 1000 through your gun. Don't worry about groups or even hitting the target, just shoot it. Then get the Straight Shooters sampler, and figure out what shoots best. I got my first "adult" airgun about a year ago, a .177 CFX. Out of the box, it loved Crow Magnums. Once I got past the break-in period, it shot it's best with JSB Exact 4.52's. After I installed a Theoben gas ram, it's best all around pellet was and is the RWS Superdome. And after you've gone through all that, get a PCP :-)! Sorry, I couldn't resist. But it's been a long day, and sometimes, I just crack myself up. Later.
Dave