The Tamiya is a superior package, hence you pay more. The Gear train, suspension systems, sound quality, etc are better.

HL is a great value for the money. Where else can you get a 1/16 scale tank and radio for a $100. The price is unbelivable. This combined with all the after market stuff that is now available makes them fun in the long run as well.

There you have it in a nutshell. Two great sources of tanks. Those that ignore the other are missing out IMO.