I start my own seed.  My stand-bys are:  Rutgers, Celebrity, Dona, Carmello, and Better Bush.  I also like Homestead, but I used the last of my seeds last year.  I also like to try other varieties and will purchase a different one every couple of years.  I tried Early Girl years ago and didn't think it was that great.  A friend swears by a variety called Jet Star, but I've never grown it.

And an FYI... If you choose to start your own, don't feel that you need to sow all the seed in the packet.  I had some Delicious seeds last 10 years.  I finally tossed them last year.  I purchased the packet when seed companies were selling by the 1/4 oz, rather than by the amount of seed.