Ampharos is not only my favorite Generation 2 Pokemon but my all-time favorite Pokemon, too bad it took me until SoulSilver to realize that! I literally stomped the yard with that thing including the battle with Red, now anytime I play a game with Mareep readily available (which sadly is really only Silver, Gold, HeartGold, SoulSilver, and you can snag a Flaaffy in Colloseum and snag a Mareep in XD) I always catch one and train that bad boy/girl into an Ampharos.
A close second for me is Meganium though, I don't care if all the odds were against it in Johto, I just love that thing! <3