Even before Inter Milan were formed, AC had wrapped up their first league championships, winning in 1901, '06 and '07.
A good headstart—but after the split and the subsequent formation of Internazionale, AC Milan did not win another league title until the 1950s.
Inter didn't take long to find their own success, with a top flight championship arriving in 1910, just two years after their inception.
Before AC's fourth title arrived in 1951, Inter had amassed five of their own already.
Between them, the two clubs won 11 Serie A titles in the 50s and 60s, with further success coming in the European Cup, which was won twice each—AC in '63, Inter in '64 and '65 and AC again in '69.
From 1970 until 2005, however, Inter won just three further league titles (and three Italian Cups), while AC Milan dominated the 1990s, winning five league championships that decade alone and adding three further European Cups in '89, '90 and '94. AC were also crowned the world's best club after winning the Intercontinental Cup in '89 and '90—though Inter's three UEFA Cups in the '90s is also to be respected.
Since the turn of the century it has been Inter, though, who have been the more trophy-laden team, with AC adding two leagues, one cup and two Champions League titles compared to Inter's five leagues, four cups and 2010 Champions League title.
Overall, it is almost neck and neck, with 47 total trophies facing off to 39 in favour of AC.
Verdict: Inter take this one. Eighteen league wins apiece is hard to call, but Inter's record five in a row was a magnificent achievement irrespective of circumstances. Inter lead 30-29 in terms of domestic trophies.