I haven't tried any 'on game' yet, but I've been very impressed by the French-made Estate OO 2.75" loads that have been sold by Midway at a great price for a while now: http://www.midwayusa.com/product/953219 ... -9-pellets
I think you'd be hard pressed to find better performing 'traditional' buckshot, and this stuff is a terrific buy while Midway has it. I don't think it'd be much of a long range load, but inside of thirty yards it has patterned very well out of numerous guns for my buddy and I. The shells are clean, well made, and the loads hit hard on both ends - recoil is stiff but tolerable in our pump guns, and slightly better out of my Remington Model 11.
I'm sure the best overall buckshot is probably the the copper or nickel plated stuff, but of that I've only tried the copper plated OO Federal in the 3.5" loading. It hits hard, but didn't pattern noticeably better out of my Stoeger P350 than the much more basic Estate stuff did. Supposedly, Dixie's heavy-duty Tri Ball buckshot is good stuff, but I've yet to try any of that either: http://dixieslugs.com/products.html
For the money, I don't you can beat the Estate loads for value and all-around performance. At normal shotgun ranges, I would expect them to perform well on deer or varmints, assuming they pattern well enough in someone's chosen gun; from what I've seen of the stuff, running it in several guns with chokes ranging from Cylinder to X-Full, it is pretty forgiving in that regard.
~ SH ~