I will take 5100J instead of 5350R.
Mainly following reasons:
1. 5100: a unique case, a unique form movement, 10 day power reserve, movement with gold chatons (very unusual at Patek), a limited edition (1500 pieces for J) for an important year 2000
2. Annual calendar is not the purest complication (very personal opinion) in general, the case is same as the massively produced 5146
3. If I have to choose one of the annual calendar advanced research pieces, I will pick 5450P, which is the final most complete one with three innovative parts in the movement.