What decade do you consider the 'Golden Era' for oddballs? Judging from the love Kellogg's and Hostess cards get on the blogosphere, I'm guessing your answer is the '70s. The only other possible answer (for me, anyways) would be the 80s and even the early 90s, when an explosion in special boxes sets and food-issues took place. Collectively, the former probably out-weighs the latter but none of those junk-wax era products can match the love of those grease stained or lenticular cards.
While I prefer oddballs from the junk era, my absolute favorite oddball from any era is this 1979 Hostess Dale Murphy card. Long on my wantlist, I received this as a birthday gift from my wife a few years ago. As tempting as it is to try to break out of the case, I think I'll just keep it as is.