Basically anything you'd find on SimpleTweaks or similar low-hanging-fruit QoL plugins, e.g.,:
- The ability to set the default position on confirm popups or skip them outright. Have a list of categories and sub-categories, and allow us to toggle the default between [Default to Yes], [Default to No], and [No Confirmation].
- Ability to filter banners/pop-ups.
- Actual percentages shown for our Secondary Attributes (18.3% Crit, etc.).
- Barrier HP properly showing on Parameter Bar.
- Option to showing EXP (only or also) as a percentage.
- Options for hybrid Legacy/Standard movement.
- The arrangement gear slots (most notably due to where the Soulstone is placed) not being a mangled puzzle.
- The ability to remove titles from UI components, do you don't have to waste screenspace for the UI to tell you that the list with all your party members on it is your Party List.
- Minimap customization.
- Hide filters, so that I can have my hotbars hidden while out of combat and weapon sheathed unless holding a chosen mod key.
- Customization for Parameter Bar, Progress Bar, Target Progress Bar
- Customization for filtering Status Effects and displaying one's own (de)buffs larger than others'.
- Larger, more readable cooldown text.
- Etc.
Alongside some others that come to mind, such as...
- Showing on a cooldown slider the time until certain party actions (e.g., raidbuffs) are readied.
- Your buffs' icons show the time remaining for that buff (moving CCW and lit before reversing direction to show the remaining cooldown, if on a CD).
- Give us straight up 10 Status Effect bars to filter and place as we will, permitting or forbidding redundancies (e.g., Straight Shot Ready appearing on multiple bars) as we like.
- AoEs showing a subtle ripple or pulse twice over their indication period, to reveal when they'll go off (actuating when the second pulse reaches the edge).
- Chat fades message by message, after a certain time, with the option to make messages from certain sources (friends, certain LSs, FC chat, etc.) fade more slowly.
- Chat bubbles, ofc.
- "Relative potency" indication. For instance, in order to get the potency for a BLM's Fire spell under AF3 capable of being evenly compared with a Melee's or Tank's attack, you'd have to multiply its potency by 180%, by 130%, and by 123%. With this option on, those with damage buffs (passive or active) would see those amounts represented in their tooltips.