[totes]

If the budget truly works either way, I would go with a Marvin clad in a heartbeat.
What I planned to use as interior finish/ window trim would be a factor as well.

 

[totes]

Planning to have fully cased windows in at least most locations.

If I was going with a natural finish casing, I would definitely go with the natural finish window. I'm a big fan of that look.
If it's going to be at the standard white painted MDF trim around the window I would seriously consider a vinyl Milgard exterior painted window.

 

[totes]

I have been using white primed finger jointed wood for jambs, much better then MDF, IMO

My lungs and I agree with you 100%.
Most paint grade is called out for Mdf in my world, especially spec work.