Smith & Wesson M&P 22 ammo ?
X2 re Ditto's & Shadling's comments.
The conventional wisdom that "the gun will tell you what it likes" applies to your M&P 22 as well. In general, if you encounter any FTE problems, the high-velocity recommendations will mitigate that, as will sticking with a somewhat heavier (40 grain) round.
That particualr gun isn't notoriously picky about ammo, but neither are 22/35's, and as Shadling noted, they don't all behave identically.
You might want to try running some 36gr rounds (i.e. CCI Mini-Mag 36gr) thorough it as well, just to see how they work in your gun. That way, you will know whether they behave well when you see some great deal on a bulk package some time in the future.
Agree all the way with ditto's comments on high velocity. As far as brand with a .22 pistol my experience is you never know till you shoot it, especially with low quality bulk ammo. I'll have one ruger 22/45 lite that shoots crap remington thunderbolts insanely well. And then have another 22/45 that shoots crappy federal ammo well but doesn't shoot remington well at all. So with the bulk crap you never know. However, in my experience if you buy better grade ammo it will shoot better and more consistently through several guns. For example most more expensive CCI ammo will shoot pretty consistent through most of my pistols. My advice is if you find an ammo your smith likes buy alot of it.
In a smaller semi auto like this I would recomend a high velocity round, not that it's going to generate all that velocity in the short barrel but the increased preasure will aid in reliability.
I don't really prefer one brand over another except that I've been constantly diapointed with Remington 22 ammo.
For accuracy you will have to try different ammo to see what your gun likes best.