So you want to invest in bullion. As they both are stores of value and a hedge against inflation, which one should you buy? This depends on a variety of factors including the amount you wish to invest as well as your goals.
If your goal is to protect a significant portfolio from inflation by investing in bullion, buying physical silver bullion may be problematic. A hundred thousand dollar investment in silver would take an SUV to move and a comparable volume to store, not to mention weighing over 250 lbs. A $100K investment in gold in contrast, would be just over 2 tubes of American gold eagles and would fit in the palm of your hand.
If you are preparing for an economic collapse, bartering with gold would present a small change problem. Even grams, which are widely available, are currently $70 each which is a pretty big number for bartering. Silver is divisible to the gram level, which is only $1.50, comparable to 90% dimes. Preparers for economic collapse or "preppers" need to stock both gold and silver in a variety of formats.
If your goal is to speculate on the price movements of metals, you should buy one or the other depending on the movement in prices. The ratio of gold to silver is currently 86:1 and has tended to be a bit lower, which would seem to bode well for silver at the moment, but excursions above and below have been common. You would also need to be aware of current events lest a sudden outbreak of peace in the Middle East or elsewhere may derail your investment plan.