Do you want less work, a stronger final result or you don't care as long as it's pretty?

It would be more work to machine both, but it would be a stronger system
It would be less work to machine one or the other, but you'd end up with a weaker setup.
The cheapest and strongest would be to buy a 22.1 stem, but it wouldn't have the look you want.

forged vs machined is a moot point in this case. And irrelevant in many cases because it ultimately depends on the design of the system, and not just one manufacturing process.

You're reducing the material in a high stress zone, so the less you do the better.