Well, it all depends on what you have in mind for your car. According to the folks at Bowtie Overdrives a properly prepared 700R4 is a pretty good deal;

"They will handle a steady diet of around 450/500 hp and 400/450 ft/lbs. of torque. This Level Transmission is definitely a huge step up from what the popular brand name companies' offer (according to their descriptions) and they still charge more! We have sold thousands of this Level Transmission over the last seven years with tremendous success. This is our most popular Level Transmission with years of refinement that's proven to be very reliable and tough in serious street performance vehicles."

http://www.bowtieoverdrives.com

I have not used Bowtie, but hear good things about them and they seem to have a lot of good information on their site - you may want to check them out.

Good luck and welcome to Club Hotrod,
Glenn