Which celebrity was plucked off magazine racks most often by consumers in the final months of 2001? "Friends" star Jennifer Aniston, 33, reigned supreme, reports the industry publication Media Industry Newsletter, which released a list of the best and worst-selling covers of last year. Aniston, who first proved she was a publisher's dream with her memorable debut in the buff on the cover of "Rolling Stone" in March of 1996, ranks with both men and women, reports MIN. In the final months of last year, she appeared on best-selling issues of "Elle," "Redbook" and "Ladies Home Journal" (which also featured her husband Brad Pitt). According to the newsletter, some of the other hottest issues of the last quarter included Madonna on the cover of "American Photo," actress Reese Witherspoon on "CosmoGirl!," Julia Roberts on "Good Housekeeping" and Faith Hill on "InStyle" (which, like PEOPLE, is owned by AOL Time Warner). But a celebrity picture doesn't necessarily guarantee a sell-out issue. Some of the worst-selling issues, according to MIN, included Mariah Carey on the cover of "Architectural Digest," Sarah Jessica Parker on "Harper's Bazaar" and comedian Jon Stewart on the cover of "Esquire."