CREATE TABLE table_203_391 (id DECIMAL, "season" TEXT, "greek league" TEXT, "greek cup" TEXT, "europe" TEXT, "coach" TEXT, "roster" TEXT)

vasilis goumas or antonis christeas participated in more championships ?
SELECT "roster" FROM table_203_391 WHERE "roster" IN ('vasilis goumas', 'antonis christeas') GROUP BY "roster" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "roster" FROM "table_203_391" WHERE "roster" IN ('vasilis goumas', 'antonis christeas') GROUP BY "roster" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1