As a G owner, I’d say it all depends on the person.
Honestly, I have not heard many ‘great’ reviews on the G Convertible.
(here’s one)
2009 Infiniti G37 Convertible - The Car Connection
Gorgeous car though, and I love the hardtop.
If you enjoy decent trunk space, need versatility, need the rear seats, need the luxury touch, would like something more ‘civilized’, will do the long trips, got a family, then the G is for you.
I’d think the ZR would be a good ‘weekend car’ to have some crazy fun in, look ‘kick-***’ cool, do mods and what not… I wouldn’t know much else b/c I do not own one.
Hope that helps though.
edit* forgot to mention the tech features on the G