NewGame Plus has it's own speedrun category as its route is very different from the usual any% route. The biggest advantages of NG+ is that you are able to RBA as child link and Farore's Wind Wrong Warp which opens up alot of possibilities.
Currently the most useful item to start with is Farore's Wind, due to the ability to wrong warp to cutscenes such as Nocturne, Silver Gauntlets, and even the credits. You can read about different item benefits here.
The downside of NewGame Plus is that saving and dying makes the B button blank unless you have a sword on B. The only way to save without losing your item is to save while you have the fishing rod on B.