Remove cream cheese, eggs, and sour cream from refrigerator at least 1 hour before baking. Preheat oven to 325°F (163°C) and position rack in center.
Combine graham cracker crumbs, 3 tablespoons sugar, and melted butter in a medium bowl. Press firmly into bottom and slightly up sides of a 9-inch springform pan. Chill for at least 10 minutes.
Wrap the outside of the springform pan with two layers of heavy-duty foil to create a watertight seal. Place a large roasting pan on counter to fill with hot water before baking.
Beat all 4 packages of softened cream cheese on medium speed for 2 minutes until smooth, scraping down the bowl. Add remaining 1 cup sugar and beat on low until combined. Mix in vanilla and sour cream, if using. Add eggs one at a time on lowest speed, mixing just until each yolk disappears.
Pour filling over chilled crust and smooth the top. Place springform pan in roasting pan, then transfer to oven. Pour very hot water into roasting pan until it reaches 1 inch up the sides of springform pan.
Bake at 325°F for 55-60 minutes until outer 2-3 inches are set and center has a slight wobble. Do not open oven door during first 45 minutes. Turn oven off and leave cheesecake inside with door cracked 1 inch for 1 full hour.
Remove pan from water bath, remove foil, and run a thin knife around inner edge to loosen. Cool completely at room temperature for 1-2 hours, then refrigerate for at least 4 hours or overnight.
Unclasp springform ring and lift away. Slice with a hot, clean knife, wiping between cuts. Add desired toppings just before serving.