ATS! it is expensive, but with the 2 mpg increase for city driving it has payed for itself over and over. it is very low stall, and is AWESOME at very low rpms, or launching from a stop with a huge load. TC lock up is excellent with this converter because instead of using a single clutch plate like most stock and aftermarket units, they have a 5 plate setup capable of holding something like 4000ft/lbs (this is what they advertise, so take that as far as you like)
while i had the torque converter/trans. out, i also did an ATS pump upgrade, wich i would highly recomend as well. it makes the pump perform better, and they instruct you to drill a .0125"? (really tiny) hole in the pump body to supply oil pressure to places in the trans that didnt get forced lubrication from the factory design. shifts are more firm, but not harsh with a stock valve body.
my TC went at around 90,000 miles, and i now have 175k on the original trans. when i change the fluid, its not burnt, and there isnt a lot of clutch material like i would get when it still had the factory setup.