Playing the Dodgers in a one-game playoff is 100% better than not making the playoffs. I agree that I'd rather play the Giants, only because of the recent postseason history of the two rosters. But I'm not silly enough to think the team with a better record than the Dodgers is a pushover.
The Giants roster doesn't look impressive, but they lead the MLB in HR in a huge ballpark, and are 6th in runs scored. And they are 2nd in team ERA (behind the Dodgers). The teams are equally formidable. In a one game playoff, it boils down to who is pitching that day, and how they are pitching. Either way, if the Reds hold on to their spot, they are flying out west for a game. They will be huge underdogs. But they will not give up. Love watching them battle.