Depends on how "late", in "later this year", is. NZ are about to start refurbing their fleet morphing into Business, Y+ and Y cabins, with true lie flat "units" in J cabin. If it's an earlier "later" this year, no guarantee on what you will get, except maybe via SFO as NZ are putting their 777's with the new configurations onto that run first.
If it's late late this year, then there is a good chance some/most of the 744 fleet will be refurbished as well, opening up LAX as a gateway.
The NZ website has good info on their new cabins and the NZ forum further up the forums here also has great info in a couple of threads.

Definitely worth a "go" if it's later this year and you can be virtually assured of getting a new config aircraft. The new product looks to be top notch and should be a winner for NZ combined with their usually above average service others talk about.
The current J cabin on NZ however, is showing it's age in my view. They still get great reviews for service, but the product itself is letting all that good work down. (Older style seats with only 50" pitch and the suchlike.)
If choosing the NZ option, pick your AKL-SYD flights with care - some of them are run with A320 equipment so it's not a true J cabin as such, although for the three hour flight it probably won't be much of an issue.

A very base chalk board summary for the three SouthPac-NthAm :-: carriers -

UA - Daily SFO-SYD daily LAX-SYD
- 744's - upper deck (6 rows 2x2, 1 row with just 2) & zones B (3 rows 2x3x2) and some of zone C (3 rows 2x2 with galley seperating each side then 2 rows of 2x3x2) on lower deck.
- 55" pitch, 20" width
- In seat video - set offerings per channel (ie - not AVOD).
- Meals served by tray with main course bought out seperately.
- Shortest travel time to SYD.

NZ (Current config) - multiple dailies SFO/LAX to AKL then 5 daily AKL-SYD.
- 744's nonstop & 763's doing an Island hop from LAX down the Sth Pac to AKL.
744's - upper deck (8 rows 2x2) and Zone B lower deck (4 rows 2x3x2)
763's - 4 rows 2x2x2. (Nasty on such long hauls - personal view).
- 50" pitch on all types.
- In seat video - set offerings per channel (ie not AVOD)
- Meals served by tray with main course done seperately
- Longer travel times to SYD.

AC - Daily YVR-SYD either via HNL or some times per year nonstop.
- A340 - 5 rows 2x2x2
763 (a) - 5 rows 1x2x2
763 (b) - 6 rows 2x2x1
- 65" pitch (some 763 configs in 1 or 2 rows have 60")
- In Seat Video on A340 and 763(b) with set channel scheduling. (Not AVOD)
- Personal DVDman on 763(a) - select your own viewing from the library on board
- Meals served course by course (no trays) as if in a restaurant. Massive service takes about 2 hours to get through. Order breakfasts a la hotel room service. Order what you want and when you want it served.
- Longer travel times to SYD.

Personally, it's such a long overnight trip I go for the "comfort" factor rather than service levels factor. (You can't see if the Flt Att is smiling under closed eyelids, can you?!?) The crews on all 3 tend to be senior so can be blase in their service. Each to each own though.
AC's new refit of it's 763's and new 777's coming on line next year should also create a top notch cabin, giving two very top of the line options for :-: on SthPac-NthAm routes by NZ/AC.