3 out of 5, just in case it goes to 5. Then I can say "Yep... I played a 5 setter" But I rarely ever play best 3 out of 5, because I'm not an outstanding player, and my fitness isn't good enough for 5 sets, so the level drops severely as the match goes on. And also because I only play tennis once a week, so there aren't too many opportunities.
I play best of five sets once every week, I never get tired because of the adrenilen (dunno how to spell). The longest match i played I won 16 46 75 76(6) 86 - was down 5-1 in the fifth and down mp and i saved it with a drop shot winner hehe the guy i was playing was like u are joking, and after that the momentum totally swung, lol i was so proud.