Shares of real estate investment trusts have soared this year as the economy has been recovering from the worst of the coronavirus pandemic. Because of the recent spike in delta-variant infections, we’re not out of the woods yet. But investors remain confident.

Some of the best performers in the REIT sector this year have been companies focused on investments that were hit especially hard during 2020 — retail and office properties. Looking forward, an emphasis on quality might serve investors well, rather than trying to catch...