All depends on what you want to do with the engine.
The TBI is good for factory engines and has a good cold start and idle at any temp. The TPI looks better performs better and I thing has a better idle quality.
If you compare induction to induction I think the TPI wins hands down. Better performance, better fuel economy, and better looking.
I have a complete TPI set up with the upgraded runners, just waiting to be installed on a engine, problem is I have had this set up for at least 2 years, but since upgraded to a LT1 engine. So the TPI just sits on the shelf. I think for the money the TPI is worth it. Just my .02