That's probably true, but Seinfeld was groundbreaking (few story arcs, no moralising, no "cute kids", no pandering to the audience) where Curb is a more polished and dangerous "that's some penis your boy has").
And the entire Costanza family are probaby my favourite TV creation ever. Many's the time I have to may to myself "Serenity now!" while reading posts about my club.
I own both (and actually paid for them) series on DVD and do watch Curb a lot more but for me it is lke Seinfeld 2, and would not exist without Seinfeld 1.
Plus nobody ever got called a Carwash cnut in Seinfled.