I've owned and used all three of the lenses you're considering, and I would go with the 50mm f/2 unless I thought I might want/need an autofocus Nikon in the future (sounds like you don't plan to go that route). The odds of an older manual focus Nikkor "breaking apart" are slim. They're built very well. Like others here, the normal lens I finally settled on is the 50mm f/1.4 Nikkor. Mine is an AIs, I picked it up for $75 from a local camera store; cosmetically, it's a beater but the glass is perfect (and this way it matches my F3, which is also quite experienced).