Main tire factors:
1) Rolling resistance
2) Traction
3) Suppleness/flexibility
4) Flat protection
Other stuff-- Weight, mounting difficulty
A given tire can be good or bad in all of these categories. Generally, better flat protection comes at the price of weight & flexibility.
TPI isn't really a good indicator of anything because of the variance between different brands. Within a brand, higher TPI usually indicates a more supple tire. For example, a Michelin Pro 4 SC is 110 TPI (the SC Comp is 150 TPI), and Continetal GP 4000sII is 330 TPI. Most people would consider these tires roughly equivalent. A Gatorskin tire is 180 TPI (really 3x60 TPI), but clearly not in the same performance category as a Pro 4SC.
Edit: For clarity, see comment below.
Last edited by gsa103; 04-17-14 at 10:19 AM.