I am planning on building a ICF home with a metal roof and I was trying to see if metal framing for the roof is worth the additional cost vs wood framing the roof?

Where is the roof or attic insulation going to be, and will it be penetrated by the framing?

The current plan for insulation is spray foam the rafters

With metal rafters, there is a very serious amount of thermal bridging undercutting the performance of the foam. It's better to use rigid insulation above the roof deck if your rafters are steel.

What Dana said. The only metal raftered building we've done had SIPS on it. You need the thermo break.

If you're in an area where trusses are commonly used then I think wood trusses is the better way to go. If you're going to hand build the rafters then cost and thermal considerations are the factors. As has been said wood is better thermally.