what pot for a soda can stove?

Generally you will get more efficiency out of a wider pot ( the exceptions are custom made set ups such as the Caldera Cone…), so something like this one is often suggested :
http://www.antigravitygear.com/proddetail.php?prod=MK3CNS

Franco

The MSR Titan Kettle works well with the soda stoves that I have made.

I second the titan kettle.

It's a fantastic size for freezer bag cooking for solo or 2 person trips.

Remember, however, that aluminum transfers heat better than titanium. Even though a titanium pot is more durable, an inexpensive aluminum pot (ie. Walmart's Grease pot http://zenstoves.net/Pots.htm) may transfer the heat better. This translates to more efficient fuel use.