I have tested many mods during the years I have been playing VP, these are the ones I am currently using:
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
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+ - Edit anything, can be used to fix certain bugs
(CulDiv) (Art) Splash Screens - Adds new era splash screen based on civ culture group, very flavourful
City-State Leaders for VP - Nice flavour mod
Music Changer - 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
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
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 France/Aztecs that can snowball very hard, it even has an animated leader screen!
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)
Current and future testing:
Non-Randomized AI Decisions - Makes the AI make better choices on lower difficulties
Hex Conquer for VP - Can conquer enemy hexes on certain conditions
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.
Thanks to all modders who take the care and time to publish and update their work!