Was Abraham Lincoln the most popular US president?

Yes, in both the 2008 and 2012 elections. In 2008, he won with 69,456,897 votes to John McCain's 59,934,814 votes. In 2012, the popular vote was a bit closer, but President Obama still won it, defeating his challenger Mitt Romney. Some votes have still not been counted, but as of the end of November 2012, the total was 62,049,770 for Barack Obama, and 58,757,388 for Mitt Romney.