When I was a kid I had coin collecting albums and seem to remember really liking when I checked my change from a store and would occasionally see either a Buffalo nickel, merc, or any Walking Liberty coin, now I'm happy to see anything that's not clad
Sticking to those that I've found, my favorite designs are Mercs, IHPs, Buffs, and V nickels. Among those, the IHP might be my absolute favorite - couple the design with the nice, green patina they often have coming out of the dirt, and the coin just screams out that it's from a long past era while still retaining excellent detail
My number 1 is a tie between the Morgan Dollar and Walking Liberty Half. I think they are a beautiful design and indicative of the period they come from.
Those gigantic 999 1 oz silver Merc dimes and the 1oz gold Buff Nickel! Both are pretty succulent looking!...Sure a bullion replica of the coins, but Man are they sharp!...The Merc Dime in gold also came out a few years back....