I typically use the tightest radius die I can for the wall thickness I plan to use... It depends on what you plan to do with it honestly.
If you are thinking about making exhaust with it, you'll find the minimum wall thickness is gonna cause issue and you'll likely want to just buy the bends. If you are gonna do framework, then a tight radius is nice...
I get all my dies through TMR Customs, they beat everyone's prices on JD2 or Pro-Tools Dies...