Spurs vs. Warriors, it's a tough call, but I feel the strength of the Spurs to overcome the Warriors will be predominantly in the control of the boards, rebounds, etc. Taking a look at the past games, the Spurs seem to take the upper edge on some of the essential parts of the game, and will use that to their advantage and beat the Warriors.
In a game such as this one, home field is often the difference, this matchup will be no different, as the Warriors are nearly unbeatable at home. The Warriors are also such a balanced team, which Stephen Curry has an off night, Klay Thompson shoots the ball well. Draymond Geen has also emerged as a force, and don't forget about finals mvp Iguodala. Tim Duncan is also not playing in this game so that won't help the Spurs either.
San Antonio is a team with a lot of spirit. Terry Scotts is a great coach, Aldridge does a great job, and the team has continuity in its line up - they guys know how to play together. Warriors interim coach Luke Walton is very good but just not as strong as Kerr. But that just won't be enough to get the Spurs past the Warriors. The Warriors have a near invincible line-up, continuity, and the confidence that comes from success.
The Golden State Warriors are one of the most difficult teams to beat in sports, because they have no discernible weaknesses. Steph Curry is impossible to guard and the rest of the squad are more than capable of pulling their weight if Curry is put in double coverage. The Spurs are good, but with no weaknesses to exploit, it all comes down to raw talent, which gives the Warriors the edge.
The Spurs won't beat the Warriors because the Warriors have more of a team style of playing. The Spurs play individualistically. They don't pass the ball and they don't execute many group plays. Although the Warriors don't have the number of stars that the Spurs have, the Warriors gel as a group. Ultimately, group play will win over egos.