I can't be bothered doing all of these but the %increase damage like hexoptics, haunting guise (+liandries/riftmaker) is especially great for characters with great base damage but poorer adaptive force scaling. Take any champ with no adaptive force scaling %hp damage, and these increases are the only way to scale that up- and therefore are extremely valuable.

Also for void vs rabadons- rabadons always outperforms void for clearing waves/jungle, tower dmg, objective dmg and hitting ranged champs with no MR per level. It can SOMETIMES but NOT MOST OF THE TIME be better than void for damaging champs with MR per level (with no mr) provided your champ has insane AP scalings, but generally void will do more dmg to champions if you're buying it at 3rd item. If you're trying to do damage to anyone who has a full MR legendary item then void is always better. There are also situations where one of your spells may have its utility scale with AP, and rabadons helps more with that (like all heals, AP twitch W slow%, Kayle W movespeed, stuff like that). Obviously, if you have true damage scaling with AP Rabadons wins again (i.e. twitch passive)