Bay Area is unusual β the stadium is in Santa Clara (45 mi south of SF). Pick a base by tradeoff: SF for the iconic city, Santa Clara/San Jose for matchday convenience, or Mountain View / Sunnyvale as middle ground.
For groups of 4+ or week-long stays, apartment rentals in the Mission, Hayes Valley, North Beach (SF) or downtown San Jose / Santa Clara often beat hotels on per-person cost.