I have tested many mods during the years I have been playing VP, these are the ones I am currently using on VP 3.10.14:
UI/QOL:
(text) Promotion Overhaul for VP (v37) - Great UI mod for clarity on promotion texts
(ui) Meaningful Colours (v 13) - Another great UI mod that makes it easier to distinguish between city-states
(ui) Trade Opportunities for VP (v12) - Generates a list of available resources from other civs, essential when playing with the Netherlands
Religion - Recurring Purchase Notify (v 1) - Essential mod that adds a notification each time you have enough faith for a missionary/inquisitor/building, prophet, GP, etc. Sadly I cannot make it work with the latest versions of VP.
Commander Influence Borders for VP (v1) - Nice UI mod to tell if a unit is being boosted by a GG/GA
Historical Religions Edit (BNW or GK) (v 45) - Adds 13 new religions for a total of 26
Improved City View (v 20) - Essential UI mod for easier control of production focus and specialists
Quick Turns (v 10) - Essential if you like to play with combat animations on
Slightly Faster Animations (v2) - Essential if you like to play with movement animations on
Sukritact's Civ VI Style City Names (v 1) - Slightly randomizes city name generation to avoid seeing the same names over and over again due to how Civ 5 assigns city names
UI - Small Resource Icons (v 4) - Cleans up the map
InGame Editor+ (v46) - Edit anything, can be used to fix certain bugs
(CulDiv) (Art) Splash Screens (v1) - Adds new era splash screen based on civ culture group, very flavourful
City-State Leaders for VP - Nice flavour mod
Music Changer (v2) - Simple button to skip the current song, just make sure to edit the UI xml file to adjust the position
Gameplay:
Better Lakes for Vox Populi (v 2.5) - Makes lakes more interesting
Global - Faith Purchases in Puppets (v 1) - Allows you to purchase some units/buildings with faith in your puppet cities
Purchase Civilians in Puppets (v2) - Allows you to purchase workers and workboats in puppets, very useful when capturing distant cities
RemoveBanLuxury (v 1) - Makes world congress sessions much more intense
(over) More Unique Components for VP (v 86) - Essential mod, takes gameplay to a whole new level, can't imagine playing without
Recon Pay Terrain Cost (v2) - Great mod that makes terrain features more like the natural barriers they should be for recon units.
Hex Conquer for VP (v4) - Can conquer enemy hexes on certain conditions, makes borders much more dynamic
Non-Randomized AI Decisions - AI makes better choices on lower difficulties
New Civs:
Cambodian Civilization for VP (v17) - Fun civ to go crazy with wonders and great engineers
Colonialist Legacies' - Phillipine Republic for VP (V12) - Cool civ similar to Portugal but encourages you to trade with others civs instead of city-states
The Goths for VP - Fun civ similar to old France/Aztecs that can snowball very hard, it even has an animated leader screen!
Current and future testing:
Leugi's Israel for VP - Interesting tall religious civ
Exploration Heritage (v37) - Universities grant a heritage promo that gives bonus XP to recon units after combat
Natural Wonders Icons Remain Visible - I have embarassingly missed some natural wonders due to them being too similar to normal terrain (I'm looking at you, Old Faithful) Does not work.
CowWarrior's Resource Filter - Tool to find resources in the map (it is missing the extra resources from VP, but it is useful to find strategics and antiquity sites) Missing too many resources.
Mods I have tried but don't personally use:
Enhanced Air Warfare - Too many new units, I felt I needed to upgrade every couple of turns
Enlightenment Era VP - Used this one for a long time until I realized it only makes the game longer without really adding anything new. Also I found too many inconsistencies and conflicts.
More Wonders for VP - Too many wonders, too many crashes
Unique City States VP - Very fun, but I felt the balance was off
Even More Resources for VP - Very cool but I found it to have too many compatibility issues, might give it a second try soon
(7) Community Events - I like the event system but there isn't a lot of compatiblity with new civs and sometimes the events didn't work
(CulDiv) (Art) Art Styles - Adds embarked unit and city models based on civ culture group. (Update: It is a nice mod but it increased crash frequency)
Thanks to all modders who take the care and time to publish and update their work!