Seven of the 10 most profitable U.S. hospitals are nonprofits, according to new research, including one in Urbana, where hospital tax exemptions are headed for a contentious court battle that soon could determine whether medical facilities are paying their fair share of taxes.The Top 10 list accompanies a study published Monday in the journal Health Affairs. The analysis is based on federal data from 2013 on nearly 3,000 hospitals. The authors measured profits using net income from patient care services, disregarding other …