Both outfielders are immensely talented, but there's one who's a clear fit for the Nationals' lineup.
Before I declare who that is, let's take a look at each respective outfielder.
Bourn is your typical speedster. He's stolen over 40 bases for the past five seasons, leading the league from 2009 to 2011 with 61, 52 and 61 steals, respectively.
He's also an above-average hitter, owning a triple-slash line of .272/.339/.365 with a .704 OPS over his career.
While not a power threat, he did hit a career-high nine home runs in 2012 as a member of the Atlanta Braves. He also hit at least 10 triples for the third time in his career.
Defensively, Bourn is a two-time Gold Glove winner (2009 and 2010). In 2010, he finished first in the league in defensive WAR (3.5). Last season, he finished second with a defensive WAR of 3.0.
Again, Bourn is your typical speedster who gets on base, steals and plays stellar defense in the outfield.
Now, let's take a look at Upton.
While quite fast in his own right, he isn't exactly your prototypical leadoff man. He has stolen over 30 bases each of the past five seasons, but he's also been caught at least 12 times in three of those five seasons.
He also strikes out a ton—134 times or more since 2007 to be exact. Last season, he struck out a career-high 169 times.
The one thing Upton provides that Bourn does not is run production. Upton has above average power—evidenced by his 28 home runs last season—and has a career .454 slugging percentage.
While his career on-base percentage of .336 is on par with that of Bourn's, Upton's .255 career batting average leaves much to be desired from the leadoff spot.
Upton is also not the Gold Glove outfielder that Bourn is. He does have a rocket for an arm, though, and that is perhaps his best weapon in the outfield. He had the most assists of any American League outfielder in 2012 with 10.
In 2008, he placed first with 16.
It's easy to see that both Bourn and Upton are very good players, both with their own set of strengths and weaknesses.
The player that best fits the Nationals, however, is Bourn.
The Nationals don't need any more power. Instead, they need a guy that can spark the rest of the lineup and make things happen with his legs.
Jayson Werth performed well as leadoff-hitter-by-default last season, but manager Davey Johnson would like him back in the middle of the lineup driving in runs in 2013.
With this being the case, the Nationals need a guy that can lead off. Upton can, but wouldn't provide the consistency that Johnson is looking for. Bourn has proven himself to be a top leadoff man in this league.
His defense would also fit perfectly in the Nationals' outfield. Bryce Harper and Werth both have tremendous arms, while their range is average at best. Bourn could get to all the balls that those two can't, making for a fine-tuned defensive outfield.
Bourn may cost a few extra dollars, but it would be worth a smart move for general manager Mike Rizzo and the Lerner Family to make the investment.
He could be the last piece that the lineup needs to propel the team to the World Series.