Nosler B-Tip is my preferred varmint round. I load some 40 grain in .223, but mostly prefer 50 grain in all .22 cal rifles so I can use the same rounds on ground squirrels, coyotes, etc. They seem to expand great even on small squirrels when pushed at around 3300 fps or faster.
The Hornady V max round is great as well, but I can drive to the Nosler plant in a few hours and have become a little partial to them. I've got a friend who shoots nothing but the Hornady soft points (the "super explosive ones, I don't know the exact lettering) and they seem to have the same effect upon varmints as the fancy plastic tipped bullets. They will expand just as well on a small squirrel. The nice thing is he picks them up on sale, I know just a year or two ago he could buy them for $9/100.
While I've tried not to bash them too hard, I cannot support Barnes Bullets. First off, they realistically are not that great performance wise. The biggest problem is they are not that accurate. But don't believe me, try them yourself. I'm biased against Barnes as they have sold sportsmen out in order to promote their own 'green' bullets. When the California Dept of Fish and Game was considering banning lead bullets in the southern part of the state, they invited Barnes Bullets in to talk about lead free bullets. Barnes representatives flat out lied to the state commission, telling them that lead free products; performed as well as lead bullets, were readily available for all calibers, that lead free ammo was readily available, that there was a minimal cost increase with lead free, etc. Unfortunately the state commission believed them, and Barnes Bullets helped to get the lead ban passed in CA. While it doesn't affect me, I feel it is only a matter of time before this kind of foolishness spreads to the rest of CA, and as CA goes, so goes the nation eventually.
Therefore I refuse to ever buy a Barnes Bullets product.