Picking your base location determines more than your starting radar coverage, it also determines what bonuses you'll have.
North America, "Air and Space" - All aircraft and aircraft weapons cost 50% less to purchase, build and maintain.
Europe, "Expert Knowledge" - Labs and workshops cost 50% less to build and maintain.
Asia, "Future Combat" - All projects in the foundry and the Officer Training school cost 50% less.
South America "We Have Ways" - Autopsies and Interrogations are completed instantly.
Africa, "All In" - Monthly XCOM funding increased by 25%.