I mostly used Dunlop Championship balls (all court and has mc enroe photo on it) because i got it from local sports authority store next to my apartment and I thought they lasted longer than wilson and penn. I got 6-pack (6x3=18balls) for $10 + salestax. I do not have rating (just started playing tennis since 3 months and picked-up the game real fast to beat a 3.5 guy in a very short period) but I now play aganist a good 3.5 guy who uses lot of top-spin. They last for one set (around 45 mins) but i use these for next couple of days as warm-up balls. I usually hit the rally as a warm-up for 20 to 30 mins and start a set with only new balls (3 balls). I should say they last for 2 hours or 2 sets before I throw it in my old ball collection basket. I heard good reviews about Dunlop grand prix extra duty for hard court balls, may be I will buy them from TW next week and see how durable are they and will post the feedback.