What types of gold do you want to buy? My suggestion is American Gold Eagles from the U.S. Mint. They are easy to store and they are easy to sell when the time comes. They often offer a tighter buy-sell spread, meaning you won’t have to pay as much in commissions because reputable dealers know they can always find a buyer for American Gold Eagles.
Gold bars are a good option too, but they may have a higher resale premium and are harder for some dealers to authenticate.