I guess I'm greedy because I want lots of all three! We are building what will be our third home. With each move we have upgraded to more living areas, more/bigger bedrooms and more yard.
We have always had a spare bedroom, that has changed back and forth in use from an office to a guest bedroom. Our new house will have 4 bedrooms including guest bedroom (we have 2 kids & frequent overnight guests), but we'll also have a large home office (I work from home), a playroom and a lounge room. So plenty of everything. If I had to choose between them, I guess I'd reduce the yard space. As my kids are getting older they don't play outside as much.