Neto, Hayward, Ingles (on a reasonable contract), Johnson, Bolomboy, Gobert, & Whithey should all be retained.
The only way I would bring back Hill is if he significantly lowers his asking price (highly unlikely) or if it's absolutely necessary in order to retain Hayward. Which, even then, would be a tough decision as I'm not entirely convinced it would be the right move, long term.
Exum/Hood/Burks/Favors/Lyles/draft picks being on the roster should be dependant on what kind of haul they could potentially bring in if packaged.
If Exum were to be traded (although it'd have to be in the right deal as I believe his potential likely far outweighs his current trade value--same as Lyles to a lesser extent), I would be okay with retaining Mack. But acquiring a stop-gap PG should be the higher priority (assuming we don't re-sign Hill).
The primary focus of this off-season needs be retaining Hayward & acquiring a 3rd star (although we may currently lack the necessary assets to do so). The rest of the roster will likely be determined by the outcome of those two scenarios.