We have VTIVX (in our Roth) and VTSAX (in our taxable Vanguard brokerage). The reality is, no matter which you choose, you're going to "feel" the swings of the market if you look at the balance too often. When the S&P500 dropped some 30%, and VTIVX was down "only" 27%, I was not splitting hairs and feeling "good" about making the "right" choice for my Roth. Instead I just focused on the long term plan for that account and maxed out the Roth contributions again, sticking to the investment plan for that account.
So worry less about which fund you choose and more about choosing and investment plan. Once you have an investment plan, then focus on getting into the mindset that you're not going to be touching that money for 10+ years (more realistically 30 if you're aiming SWAMI), so what do you care what it does in the meantime?