Aidan: Picking one, two or three of these would be tough...they are all very good to outstanding. Of course, selection also depends on what you are willing to spend. The older Van Winkles and Hirches can run well beyond $100US. Forget about Four Roses. They don't sell their bourbon here in the U.S.; it's export only. And be careful. Four Roses makes a blended whiskey that's widely available here, but is total bilge water.
If forced to choose only a few bottles, my personal preferences would be (in order):
1. Van Winkle Family Reserve Straight Rye Whiskey 13yo. (Mouth-filling goodness from start to finish. A true taste of America. My favorite American whiskey...at the moment
2. Wild Turkey Rare Breed. (A consistently outstanding marriage of 6-, 8- and 10-year-old Wild Turkey bottled at around 54%abv. So full-bodied and rounded you almost have to chew it.)
3. Wild Turkey Kentucky Spirit. (A single barrel bottling, the best of which are without peer.)
4. A. H. Hirsch 16yo. (From the now-closed Michter's Distillery in Pennsyvlania. You know how some folks lament the loss of Port Ellen? This is the American version of that story.)
5. Booker's. (A barrel-proof juggernaut that explodes with flavor and fire. Not for the faint of heart.)
However, if you or your friend are lucky enough to find a bottle of George T. Stagg 15yo or Old Forester Birthday Bourbon, grab them! I have not tasted either of these, but have read glowing reports from people whose taste I trust.