I think the GA droprate is in a pretty decent place. What is ruining it is that we still have so many bad affixes. We need to streamline this even more and add in some new juicy additions and then modifiers on how affixes can roll for fun. Here is a brief rundown:
Example Removed affixes:
Single resists on gear. All resists on weapons like mythic staff
Single resist inherents on rings. Changed to either lucky hit, damage with lightning / cold / fire / poison / shadow / physical / ect or movespeed.
Life per second
Life per hit
Lucky hit life
other bleh ones i cant think of
5 example Added Affixes:
Skilled% - Once you get this to 100% you gain a 7th skill slot. Additional % over adds to damage.
Enchanter% - Get this to 100% for additional mage enchantment slot. Mage only. Addition % over 100 adds to enchantment effect for all enchant slots. There would be at least 1 of these for each hero as an example I just did sorc.
Haste% - Attack speed and movement speed in one affix
Shell% - Damage resistance and all resists in one affix
Transmutation% - Get to 100% to Automatically changes non GA items to parts within your far range.
Modifiers for affixes. These are rare affixes in new text colors that change how these affixes work for more interaction and fun. Different zones would have different chances to have these to encourage play in that areas. 4 Examples.
Enchanted: Blue. These affixes keep their GA on enchanting and cost much less to enchant and can hit +passives easier or +core skills or + specific skills. More common to find in dungeon rewards.
Hellish: Red. These have an additional inherent affix that is only active in helltide zone.
This affix can be anything the item qualifies for. More common in helltides.
Flux: Purple. This affix is a choice of two affixes. Choose one for it to become permanently. This affix cannot be enchanted. More common in strongholds and cellars.
Holy: White. This affix is boosted by 500% while you have a shrine buff. Add 1s to shrine durations. An item can only have 1 shrine affix. More common in events.
All items should also have one of 3 different inherents it can have. This would spice up items greatly. Even items like pants without inherents. We would also have a rare drop token that would let you reroll this but it would be rare.