There are three available from behindthenet.ca: QualComp, Corsi QoC, and Corsi Rel QoC. All are calculated in the exact same way (the average of opponents' ratings, weighted by ice time), save for the base statistic. With QualComp, that basic statistic is relative plus minus (on-ice plus-minus per 60 less off-ice plus-minus per 60). With Corsi QoC, it's Corsi On (on-ice Corsi per 60). With Corsi Rel QoC, it's relative Corsi (on-ice Corsi per 60 less off-ice Corsi per 60).
I get the feeling that if you want to see who faced top scorers, you use QualComp. QualComp puts "rating" (relative plus-minus) into context, but not so much Corsi. If you want to see who faced the tougher competition, use Corsi QoC. If you want to see who the coach intended to take the toughest competition, use Corsi Rel QoC. The last two match up most of the time, but due to opponents faced differences, not always.
All comparing intra-team, obviously. Inter-team is a whole 'nuther ballgame.