sentiment – noun – an attitude or opinion

Soruce http://www.merriam-webster.com/dictionary/sentiment

For instance, three cemeteries- Palisades, Weehawken,and Holy Cross—  attracted among the strongest Twitter sentiment on the list.
From : The Saddest and Happiest Places of New York City According to Twitter

The author was trying to speak of strange anomolies in the study in the article. The strongest feelings of the strange anomolies according to Twitter users is the previous said cemeteries.