I like mostly old military bolt actions. I would say Mauser exclusively but dang it there is just something about those Mosin Nagant Russian rifles! So tough, reliable, simple, durable, accurate--enough, and just a little bit of ugly thrown in. Hard hitting caliber too! I love AK's too. About to get a chrome AK on consignment and I may just keep it. I sold it to a woman during the Obama craziness and I don't believe she ever shot it besides test firing with me behind my shop.
Anyway, I guess my favorite guns to collect are guns with history behind them. When I hold them I just think "boy if this could just talk!". I even like cleaning out cosmoline!