Interestingly, both teams have interplanetary systems nicknames, although the Cosmos nickname was originally associated to the word, 'Cosmopolitans'.
The New York Cosmos are legendary from their days in the NASL with Pelé, Franz Beckenbauer and Giorgio Chinaglia in the late 1970's and early 80's. The L.A. Galaxy have become legendary after the living legend, Landon Donovan, teamed with David Beckham and Robbie Keane to run the MLS Cup gamut a few times while creating a dynasty (three MLS Cups in the last four seasons).
According to the new Cosmos front office, their objective is to be a world class soccer club. They already have one marquee name in Raul signed to play this upcoming season (They seem to get thrown into the rumor mill on other known talent available-like Freddy Adu).
The Cosmos won the NASL Soccer Bowl a couple seasons back and are out to match their historical contributions of 35 seasons back. They are working towards building their own stadium and bringing the glitz back of yesteryear.
From 1977-1982, the Cosmos averaged more than 35,000 people in attendance for their home games at Giants Stadium and they won four First Division championships (NASL). Altogether, the Cosmos won 5 championships and 7 regular season titles in its heyday era.
The Galaxy have won 5 MLS Cups and 4 regular season titles (MLS Supporters' Shields) overall. They have been the most featured soccer club team in the media for a decade, since LD's arrival in 2005.
Beckham's ability to match Pelé's contributions, Keane's timeliness, assists and MVP have all helped the Galaxy to rise up ahead of all other MLS teams in branding and panache.
The one fault that will always be associated with the Galaxy over this time period is their inability to win CONCACAF Champions League. As it stands now, the Cosmos will have to win the U.S. Open Cup to get their chance to play in Champions League.
What keeps this discussion for cultural significance enticing is partly due to the New York/LA adversarial sports narrative. It is the opposite coasts and dominant markets in a battle for soccer supremacy.
If the Cosmos are able to pull off their unique marketing philosophy for attracting fans while playing from the disadvantage of Division Two, then, a battle for supremacy may ensue for years to come.
The Galaxy's mascot is named Cozmo. This tells us for sure how closely these teams are linked.
So, which team has had the biggest impact on soccer in the U.S? It depends on one's perspective, how much do we count the old days and the prospects for a new global team versus the champions of today who have provided the most entertaining and dramatic play of American club soccer over the last several years.
Vote in poll to the right (scroll down a bit) of the website.