What's the best macro set-up for 5n?

Compact macro lenses that I can recommend from my personal experience with NEX5N/5/3:

short

Zeiss Makro Planar 50/2 ZF (best) 1:2

Zeiss Makro Planar C 60/2.8 1:2

Leica R Macro Elmar 60/2.8 1:2

Nikkor 60/2.8 Micro 1:1

medium

Zeiss Makro Planar 100/2 ZF (best) 1:2

Nikkor Micro 105/2.8 AFD 1:1

Tamron 90/2.8 (older AFD wersion with Nikon mount and aperture ring) 1:1

Tokina ATX 100/2.8 1:1

long

Sigma 180/5.6 apo macro (beware of fungus) 1:2 - very small and very good

Others like Sigma apo macro 180/3.5,Tamron Macro 180/3.5,Nikkor Micro 200/4 are excellent but big.