If you decide to move into New Game+ you will carry over:
- Armor & Accessories (both equipped and unequipped)
However, collectibles will not carry over. This means that if you do decide to get the platinum in NG+, you will be recollecting any collectibles you may have collected in the initial playthough. Also, in NG+, enemies will scale with the level that carried over from the initial playthrough. So ideally, it will not be any easier than the initial playthrough.
The major differences between endgame in the initial playthough and NG+ is the addition of more armor sets and stronger version of previous equipment.
Basically, if you are willing to recollect all the collectibles (or complete that achievement prior to NG+), you will have the benefit of a wider range of stronger equipment to complete any extra side quests and endgame content.