the best affordable can you can muster .. what I'm saying is that there are so many options out there that you should buy the best you can afford.
personally I have an SAS 30 cal can that is rated for up to 300 win mag .. I paid 575 plus 200 for the stamp and 50 for my SOT to do the NFA transfer. I don't think you can find a better performing can for less money. FWIW SAS is the can of choice for Accuracy International!