As a kid with not much money, it was easiest to do Lincoln cents, but I also scoured the dollar (and below) bins for Indian Head cents and Buffalo nickels. Later on, I did Mercury dimes as well. Around the time I got to high school, I became more interested in foreign coinage, and I stopped working on my US sets.
After my father died, I took his collection, which included almost complete Indian Head cents, Lincoln cents, Buffalo Nickels, Mercury dimes, Standing Liberty quarters, and complete Washington quarters. I decided I should finish his sets, so I combined mine with his (only a few of mine were upgrades of his coins) and now have a short want list of some of the most famous US keys.
I’m still not too interested in US coins, but I think it’s important to complete my father’s collection, if I can get my hands on nice, reasonably priced examples of those key date coins.